Immersed rotary jet spinning (iRJS) devices and uses thereof

ABSTRACT

Exemplary embodiments provide systems, devices and methods for the fabrication of three-dimensional polymeric fibers having micron, submicron and nanometer dimensions, as well as methods of use of the polymeric fibers.

RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.14/763,620, filed on Jul. 27, 2015, which is a 35 U.S.C. § 371 nationalstage filing of International Application No. PCT/US2014/016197, filedon Feb. 13, 2014, which in turn claims priority to U.S. ProvisionalApplication No. 61/764,349, filed on Feb. 13, 2013, and U.S. ProvisionalApplication No. 61/837,779, filed on Jun. 21, 2013. The entire contentsof each of the foregoing applications are incorporated herein byreference.

GOVERNMENT SUPPORT

The invention was supported, in whole or in part, by grant numberDMR-0213805 awarded by the National Science Foundation. The UnitedStates Government has certain rights in the invention.

BACKGROUND

Electrospinning is a common conventional process for fabricatingpolymeric fibers. Electrospinning uses high voltages to create anelectric field between a droplet of polymer solution at the tip of aneedle and a collection device. One electrode of the voltage source isplaced in the solution and the other electrode is connected to thecollection device. This exerts an electrostatic force on the droplet ofpolymer solution. As the voltage is increased, the electric fieldintensifies, thus increasing the magnitude of the force on the pendantdroplet of polymer solution at the tip of the needle. The increasingelectrostatic force acts in a direction opposing the surface tension ofthe droplet and causes the droplet to elongate, forming a conical shapeknown as a Taylor cone. When the electrostatic force overcomes thesurface tension of the droplet, a charged continuous jet of polymersolution is ejected from the cone. The jet of polymer solutionaccelerates towards the collection device, whipping and bending wildly.As the solution moves away from the needle and toward the collectiondevice, the jet rapidly thins and dries as the solvent evaporates. Onthe surface of the grounded collection device, a non-woven mat ofrandomly oriented solid polymeric fibers is deposited. Zufan (2005)Final RET Report; Xie, J. W. et al. (2008) Macromolecular RapidCommunications 29(22):1775-1792; Reneker, D. H., et al. (2007) Advancesin Applied Mechanics 41:43-195; Dzenis, Y. (2004) Science304(5679):1917-1919; Rutledge, G. C. and Yu, J. H. (2007)“Electrospinning” In Encyclopedia of Polymer Science and Technology,John Wiley & Sons: New Jersey; Krogman, K. C., et al. (2009) NatureMaterials 8(6):512-518; Pham, Q. P., et al. (2006) Tissue Engineering12(5):1197-1211; Boland, E. D., et al. (2001) Journal of MacromolecularScience-Pure and Applied Chemistry 38(12):1231-1243; Teo, W. E. andRamakrishna, S. (2006) Nanotechnology 17(14):R89-R106; Li, D.; Xia, Y.N. (2004) Advanced Materials 16(14):1151-1170; Greiner, A. and Wendorff,J. H. (2007) Angewandte Chemie-International Edition 46(30):5670-5703.

There are multiple drawbacks associated with electrospinning, e.g., alow production rate, the requirement of a high voltage electrical field,the requirement of precise solution conductivity, and the need foradditional devices for producing aligned fiber structures. Lia and Xia(2004) Advanced Materials 16:1151-1170; Weitz, et al. (2008) NanoLetters 8:1187-1191; Arumuganathar, S. and Jayasinghe, S. N. (2008)Biomacromolecules 9(3):759-766.

Devices and methods to overcome the drawbacks associated withelectrospinning have been described in, for example, U.S. PatentPublication No U.S. 2012/0135448 and PCT Publication No. WO 2012/068402.These devices are referred to as Rotary Jet Spinning Devices (RJS) andallow the facile fabrication of polymeric fibers having micron,submicron, and nanometer dimensions. RJS devices permit the formation ofpolymeric fibers by essentially ejecting a polymer solution through anorifice of a reservoir into air. Air drag extends and elongates the jetsinto fibers as the solvent in the material solution rapidly evaporates.Nonetheless, in the case of slow evaporating solvents, e.g., aqueoussolvents, and in the case of reservoirs that spin at low rotationalspeeds, the air drag experienced by the material jets may not besufficient to evaporate certain solvents before they reach thecollection device. In addition, air drag alone is insufficient toprepare polymeric fibers in the case of polymers that require on-contactcrosslinking, precipitation, and/or a combination of elongation in airand on-contact crosslinking or precipitation. Therefore, fabrication ofpolymeric fibers using water soluble polymers and/or polymer solutionswhich, e.g., require on-contact crosslinking and/or precipitation, toform physically and chemically stable polymeric fibers remainschallenging.

Accordingly, there is a need in the art for improved systems, devicesand methods for the fabrication of polymeric fibers, such as nanofibers.

SUMMARY

The present invention provides systems, devices and methods for thefabrication of three-dimensional polymeric fibers having micron,submicron or nanometer dimensions, as well as the polymeric fibers thatare produced and methods of use of the polymeric fibers.

In accordance with one exemplary embodiment, a device is provided forformation of one or more micron, submicron or nanometer dimensionpolymeric fibers. The device includes a reservoir holding a polymersolution. The reservoir includes a surface having one or more orificesfor ejecting the polymer solution from the reservoir for fiberformation. The device also includes a motion generator configured toimpart rotational motion to the reservoir so that the rotational motioncauses ejection of the polymer solution from the reservoir through theone or more orifices. The device also includes a collection deviceholding a liquid and configured and positioned to accept the polymersolution ejected from the reservoir. The reservoir and the collectiondevice are positioned such that the one or more orifices of thereservoir are submerged in the liquid in the collection device. Theejection of the polymer solution into the liquid in the collectiondevice causes formation of one or more micron, submicron or nanometerdimension polymeric fibers.

In accordance with another exemplary embodiment, a device is providedfor formation of one or more micron, submicron or nanometer dimensionpolymeric fibers. The device includes a reservoir for holding a polymerand including an outer surface having one or more orifices for ejectingthe polymer for fiber formation. The device may further include a firstmotion generator couplable to the reservoir, the first motion generatorconfigured to impart rotational motion to the reservoir to causeejection of the polymer through the one or more orifices. The device mayfurther include a collection device holding a liquid, the collectiondevice configured and positioned to accept the polymer ejected from thereservoir, a second motion generator couplable to the collection device,the second motion generator configured to impart rotational motion tothe liquid in the collection device to generate a liquid vortexincluding an air gap, wherein the reservoir and the collection deviceare positioned such that the one or more orifices of the reservoir arepositioned in the air gap of the liquid vortex in the collection device;and wherein the ejection of the polymer into the air gap andsubsequently into the liquid of the liquid vortex in the collectiondevice causes formation of one or more micron, submicron or nanometerdimension polymeric fibers.

The air gap may be positioned centrally in the liquid vortex in thecollection device.

The first and second motion generators may impart rotational motion inthe same or opposite rotational direction.

In one embodiment, the one or more orifices of the reservoir are not incontact with the liquid in the collection device.

In one embodiment, the air gap is formed along a central axis of theliquid vortex and abutting the top surface of the liquid in the liquidvortex, and wherein the one or more orifices of the reservoir arepositioned below the highest level of the top surface of the liquid inthe collection device.

In one embodiment, the first motion generator is a motor.

In one embodiment, the second motion generator is a stir bar.

In one embodiment, the stir bar has a length of about 2 inches to about4 inches.

In one embodiment, rotational motion of the liquid in the collectiondevice is about 200 to about 1,500 rpm.

In one embodiment, the volume of the liquid in the collection device isabout 2 liters.

In one embodiment, the second motion generator is a drainage system thatimparts the rotational motion to the liquid by draining the liquidthrough the draining system.

The one or more orifices may be horizontally spaced from the liquid inthe liquid vortex by a distance of about 0.01 cm to about 8.0 cm. In oneembodiment, the one or more orifices are horizontally spaced from theliquid in the liquid vortex by a distance of about 3.0 cm to about 6.0cm.

In one embodiment, the ejection of the polymer into the air gap andsubsequently into the liquid of the liquid vortex causes precipitationof the one or more micron, submicron or nanometer dimension polymericfibers. In another embodiment, the ejection of the polymer into the airgap and subsequently into the liquid of the liquid vortex causescross-linking of the one or more micron, submicron or nanometerdimension polymeric fibers.

In one embodiment, the liquid comprises one or more cells, and ejectionof the polymer into the air gap and subsequently into the liquid of theliquid vortex causes formation of the one or more micron, submicron ornanometer dimension polymeric fibers having the one or more cellsenmeshed therein.

In one embodiment, the exemplary fiber formation device furthercomprises a first control mechanism configured to control a speed of therotational motion imparted by the first motion generator, and a secondcontrol mechanism configured to control a speed of the rotational motionimparted by the second motion generator. In one embodiment, the firstmotion generator is also configured to impart a linear oscillatorymotion to the reservoir.

The liquid in the collection device may be rotated at about 200 rpm orabove, e.g., about 200 rpm to about 1,500 rpm.

In accordance with another exemplary embodiment, a method is providedfor fabricating one or more micron, submicron or nanometer dimensionpolymeric fibers using an exemplary fiber formation device. The methodmay include providing the device, using the motion generator to rotatethe reservoir about an axis of rotation to cause ejection of the polymersolution in one or more jets, and collecting the one or more jets of thepolymer in the liquid held in the collection device to cause formationof the one or more micron, submicron or nanometer dimension polymericfibers.

In accordance with another exemplary embodiment, a method is providedfor fabricating one or more micron, submicron or nanometer dimensionpolymeric fibers. The method includes providing a polymer in solution,rotating the polymer in solution about an axis of rotation to causeejection of the polymer solution in one or more jets, and collecting theone or more jets of the polymer in a liquid to cause formation of one ormore micron, submicron or nanometer dimension polymeric fibers.

The present invention also provides methods for fabricating one or moremicron, submicron or nanometer dimension polymeric fibers. The methodsinclude providing a polymer in solution, rotating the polymer insolution about an axis of rotation to cause ejection of the polymersolution in one or more jets, generating a liquid vortex in a collectiondevice for collecting the one or more jets of the polymer, the liquidvortex including a central air gap, and collecting the one or more jetsof the polymer in the collection device, wherein the one or more jetsare initially ejected through the air gap of the liquid vortex andsubsequently through the liquid in the liquid vortex of the collectiondevice, wherein the ejection of the polymer into the air gap andsubsequently into the liquid in the collection device causes formationof one or more micron, submicron or nanometer dimension polymericfibers.

In another aspect, the present invention provides methods or fabricatingone or more micron, submicron or nanometer dimension polymeric fibers.The methods include providing a device of the invention, using the firstmotion generator to rotate the reservoir about an axis of rotation tocause ejection of the polymer in one or more jets, using the secondmotion generator to rotate the liquid in the collection device togenerate the liquid vortex, and collecting the one or more jets of thepolymer in the air gap of the liquid vortex and subsequently in theliquid of the liquid vortex of the collection device to cause formationof the one or more micron, submicron or nanometer dimension polymericfibers.

Rotational speeds of the reservoir in exemplary embodiments may rangefrom about 1,000 rpm to about 400,000 rpm, e.g., about 1,000, 3,000,5,000, 10,000, 50,000, 55,000, 60,000, 65,000, 70,000, 75,000, 80,000,85,000, 90,000, 95,000, 100,000, 105,000, 110,000, 115,000, 120,000,125,000, 130,000, 135,000, 140,000, 145,000, 150,000 rpm, about 200,000rpm, 250,000 rpm, 300,000 rpm, 350,000 rpm, or about 400,000 rpm. Rangesand values intermediate to the above recited ranges and values are alsocontemplated to be part of the invention.

Exemplary orifice lengths that may be used in some exemplary embodimentsrange between about 0.001 m and about 0.1 m, e.g., about 0.0015, 0.002,0.0025, 0.003, 0.0035, 0.004, 0.0045, 0.005, 0.0055, 0.006, 0.0065,0.007, 0.0075, 0.008, 0.0085, 0.009, 0.0095, 0.01, 0.015, 0.02, 0.025,0.03, 0.035, 0.04, 0.045, 0.05, 0.055, 0.06, 0.065, 0.07, 0.075, 0.08,0.085, 0.09, 0.095, or about 0.1 m. Ranges and values intermediate tothe above recited ranges and values are also contemplated to be part ofthe invention.

Exemplary orifice diameters that may be used in some exemplaryembodiments range between about 0.05 μm and about 1000 μm, e.g., about0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.15, 0.2, 0.225, 0.25, 0.275, 0.3,0.325, 0.35, 0.375, 0.4, 0.425, 0.45, 0.475, 0.5, 0.525, 0.55, 0.575,0.6, 0.625, 0.65, 0.675, 0.7, 0.725, 0.75, 0.075, 0.8, 0.825, 0.85,0.825, 0.9, 0.925, 0.95, 0.975, 1.0, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5,5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, 20, 30, 40, 50, 60, 70, 80, 90,100, 150, 200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700, 750,800, 850, 900, 950, or about 1000 μm. Ranges and values intermediate tothe above recited ranges and values are also contemplated to be part ofthe invention.

The reservoir may further comprise a first nozzle provided on a first ofthe one or more orifices of the reservoir. In one embodiment, the firstnozzle has a cross-sectional configuration different from across-sectional configuration of the first orifice. In one embodiment,the first nozzle increases the surface area of the formed fiber. Inanother embodiment, the first nozzle convolutes the surface topographyof the formed fiber. In one embodiment, the first nozzle creates one ormore structural features on the surface of the formed fiber. In oneembodiment, the structural features range in size from about 1 nanometerto about 500 nanometers, e.g., about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15,20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 90, 100, 125, 150,175, 200, 250, 300, 350, 400, 450, or 500 nanometers.

In one embodiment, the formed micron, submicron or nanometer dimensionpolymeric fiber is imaged, e.g., using a scanning electron microscope.

Suitable polymers for use in exemplary devices and methods include watersoluble polymers (i.e., polymers dissolved in slowly evaporatingsolvents, e.g., aqueous solvents), polymers that require on-contactcross-linking (e.g., alginate) and/or polymers that cannot be readilydissolved at a high enough concentrations to provide sufficientviscosity for random entanglement and solvent evaporation to formpolymeric fibers (e.g., deoxyribonucleic acid, polyurethane-polyureacopolymer, and polyacrylonitrile), and/or polymers that requireprecipitation (e.g., deoxyribonucleic acid), and/or polymers dissolvedin water at low concentrations (e.g., below 2%) and/or polymers thatrequire both extension in air and precipitation (e.g., polyamides, e.g.,liquid crystalline polymers, e.g., poly-paraphenylene terephthalamideand poly(p-phenylene benzobisoxazole)).

Suitable polymers may be biocompatible or non-biocompatible, syntheticor natural, e.g., biogenic polymers, e.g., proteins, polysaccharides,lipids, nucleic acids or combinations thereof.

Exemplary polymers which require on-contact crosslinking include, forexample, alginate, gelatin, collagen, chitosan, polyvinyl alcohols,polyacrylamides, starches, and polyethylene oxides, copolymers andderivatives thereof

Exemplary polymers which require precipitation include, for example,deoxyribonucleic acid, ribonucleic acid.

Exemplary polymers which require extension in air and precipitationinclude, for example, polyamides, e.g., liquid crystalline polymers,e.g., poly-paraphenylene terephthalamide, e.g., 1,4-phenylene-diamine(para-phenylenediamine) and terephthaloyl chloride, and poly(p-phenylenebenzobisoxazole)).

Suitable polymers for use in the devices and methods provided herein donot include those polymers that are soluble in highly volatile solvents(i.e., liquids with low boiling points and high vapor pressure), such aschloroform, about 90, 95, or about 100% ethanol, DMF (e.g., about 60,65, 70, 75, 80, 85, 90, 95, or about 100% DMF), acetone,dichloromethane, and diethylether.

In one embodiment the polymers for use in the devices and methods of theinvention may be mixtures of two or more polymers and/or two or morecopolymers. In one embodiment the polymers for use in the devices andmethods of the invention may be a mixture of one or more polymers and ormore copolymers. In another embodiment, the polymers for use in thedevices and methods of the invention may be a mixture of one or moresynthetic polymers and one or more naturally occurring polymers.

In one embodiment, the polymer is fed into the reservoir as a polymersolution, i.e., a polymer dissolved in an appropriate solution. In thisembodiment, the methods may further comprise dissolving the polymer in asolvent prior to feeding the polymer into the reservoir.

Alternatively, the polymer may be fed into the reservoir as a polymermelt and, thus, in one embodiment, the reservoir is heated at atemperature suitable for melting the polymer, e.g., heated at atemperature of about 100° C.-300° C., 100° C.-200° C., about 150-300°C., about 150-250° C., or about 150-200° C., 200° C.-250° C., 225°C.-275° C., 220° C.-250° C., or about 100, 105, 110, 115, 120, 125, 130,135, 140, 145, 150, 155, 160, 165, 170, 175, 180, 185, 190, 195, 200,205, 210, 215, 220, 225, 230, 235, 240, 245, 250, 255, 260, 265, 270,275, 280, 285, 290, 295, or about 300° C. Ranges and temperaturesintermediate to the recited temperature ranges are also part of theinvention. In such embodiments, the reservoir may further comprise aheating element.

In one embodiment of the invention, a plurality of micron, submicron ornanometer dimension polymeric fibers are formed. The plurality ofmicron, submicron or nanometer dimension polymeric fibers may be of thesame diameter or of different diameters.

In one embodiment, the methods of the invention result in thefabrication of micron, submicron or nanometer dimension polymeric fiberhaving a diameter of about 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65,70, 75, 80, 85, 90, 95, 100, 110, 120, 130, 140, 150, 160, 170, 180,190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300, 310, 320,33, 340, 350, 360, 370, 380, 390, 400, 410, 420, 430, 440, 450, 460,470, 480, 490, 500, 510, 520, 530, 540, 550, 560, 570, 580, 590, 600,610, 620, 630, 640, 650, 660, 670, 680, 690, 700, 710, 720, 730, 740,750, 760, 770, 780, 790, 800, 810, 820, 830, 840, 850, 860, 870, 880,890, 900, 910, 920, 930, 940, 950, 960, 970, 980, 990, 1000 nanometers,10, 20, 30, 40, or about 50 micrometers.

In one embodiment, the methods of the invention result in thefabrication of a plurality of aligned (e.g., uniaxially aligned) micron,submicron or nanometer dimension polymeric fibers.

In other embodiments of the invention, the plurality of micron,submicron or nanometer dimension polymeric fibers are contacted withadditional agents, e.g., a plurality of living cells, e.g., musclecells, neuron cells, endothelial cells, and epithelial cells;biologically active agents, e.g., lipophilic peptides, lipids,nucleotides; fluorescent molecules, metals, ceramics, nanoparticles, andpharmaceutically active agents.

In certain embodiments of the invention the polymeric fibers contactedwith living cells are cultured in an appropriate medium for a timeuntil, e.g., a living tissue is produced.

In still other embodiments, the polymer is contacted with living cellsduring the fabrication process such that fibers populated with cells orfibers surrounded (partially or totally) with cells are produced. Thepolymer may also be contacted with additional agents, such as proteins,nucleotides, lipids, drugs, pharmaceutically active agents, biocidal andantimicrobial agents during the fabrication process such that functionalmicron, submicron or nanometer dimension polymeric fibers are producedwhich contain these agents. For example, alginate fibers comprisingliving cells may be fabricated by providing living cells in a solutionof cell media that contains calcium chloride at a concentration thatmaintains cell viability and is sufficient to crosslink the alginatepolymer.

In other aspects, the present invention provides the polymeric fibersproduced using the methods and devices of the invention, as well astissues, membranes, filters, biological protective textiles, biosensordevices, food products, and drug delivery devices comprising thepolymeric fibers of the invention.

In another aspect, the present invention provides methods foridentifying a compound that modulates a tissue function. The methodsinclude, providing a tissue produced according to the methods of theinvention; contacting the tissue with a test compound; and determiningthe effect of the test compound on a tissue function in the presence andabsence of the test compound, wherein a modulation of the tissuefunction in the presence of the test compound as compared to the tissuefunction in the absence of the test compound indicates that the testcompound modulates a tissue function, thereby identifying a compoundthat modulates a tissue function.

In yet another aspect, the present invention provides methods foridentifying a compound useful for treating or preventing a tissuedisease. The methods include, providing a tissue produced according tothe methods of the invention; contacting the tissue with a testcompound; and determining the effect of the test compound on a tissuefunction in the presence and absence of the test compound, wherein amodulation of the tissue function in the presence of said test compoundas compared to the tissue function in the absence of the test compoundindicates that the test compound modulates a tissue function, therebyidentifying a compound useful for treating or preventing a tissuedisease.

The tissue function may be any suitable physiological activity associatewith the particular tissue type, e.g., a biomechanical activity, e.g.,contractility, cell stress, cell swelling, and rigidity, or anelectrophysiological activity.

In one embodiment, the methods include applying a stimulus to thetissue.

In one embodiment, a plurality of living tissues is contacted with atest compound simultaneously.

In one aspect, the present invention provides methods for fabricatingone or more micron, submicron or nanometer dimension poly-paraphenyleneterephthalamide fibers. The methods include providing apoly-paraphenylene terephthalamide solution; rotating thepoly-paraphenylene terephthalamide solution about an axis of rotation tocause ejection of the poly-paraphenylene terephthalamide solution in oneor more jets; and collecting the one or more jets of thepoly-paraphenylene terephthalamide in water to cause formation of one ormore micron, submicron or nanometer dimension poly-paraphenyleneterephthalamide fibers.

In another aspect, the present invention provides methods forfabricating one or more micron, submicron or nanometer dimensionpoly-paraphenylene terephthalamide fibers. The methods include providinga device of the invention; using the motion generator to rotate thereservoir about an axis of rotation to cause ejection of apoly-paraphenylene terephthalamide polymer solution in one or more jets;and collecting the one or more jets of the poly-paraphenyleneterephthalamide in the liquid held in the collection device to causeformation of the one or more micron, submicron or nanometer dimensionpoly-paraphenylene terephthalamide fibers, wherein the liquid is water.

In another aspect, the present invention provides methods forfabricating a sheet of poly-paraphenylene terephthalamide nanometerfibers. The methods include providing a poly-paraphenyleneterephthalamide solution; rotating the poly-paraphenyleneterephthalamide solution about an axis of rotation to cause ejection ofthe poly-paraphenylene terephthalamide solution in one or more jets; andcollecting the one or more jets of the poly-paraphenyleneterephthalamide in water to cause formation of the sheet of micron,submicron or nanometer dimension fibers comprising poly-paraphenyleneterephthalamide.

In another aspect, the present invention provides methods forfabricating a sheet of poly-paraphenylene terephthalamide nanofibers.The methods include providing a device of the invention; using themotion generator to rotate the reservoir about an axis of rotation tocause ejection of a poly-paraphenylene terephthalamide solution in oneor more jets; and collecting the one or more jets of thepoly-paraphenylene terephthalamide in the liquid held in the collectiondevice to cause formation of the poly-paraphenylene terephthalamidenanofibers, wherein the liquid is water.

In one aspect, the present invention provides methods for fabricatingone or more micron, submicron or nanometer dimension poly-paraphenyleneterephthalamide fibers. The methods include providing apoly-paraphenylene terephthalamide solution; rotating thepoly-paraphenylene terephthalamide solution about an axis of rotation tocause ejection of the poly-paraphenylene terephthalamide solution in oneor more jets; generating a liquid vortex in a collection device forcollecting the one or more jets of the poly-paraphenyleneterephthalamide, the liquid vortex including a central air gap; andcollecting the one or more jets of the poly-paraphenyleneterephthalamide in the collection device, wherein the one or more jetsare initially ejected through the air gap of the liquid vortex andsubsequently through the liquid in the liquid vortex of the collectiondevice; wherein the ejection of the poly-paraphenylene terephthalamideinto the air gap and subsequently into the liquid in the collectiondevice causes formation of one or more micron, submicron or nanometerdimension poly-paraphenylene terephthalamide fibers, wherein the liquidis water.

In another aspect, the present invention provides methods forfabricating one or more micron, submicron or nanometer dimensionpoly-paraphenylene terephthalamide fibers. The methods include providinga device of the invention; using the first motion generator to rotatethe reservoir about an axis of rotation to cause ejection of thepoly-paraphenylene terephthalamide in one or more jets; using the secondmotion generator to rotate the liquid in the collection device togenerate the liquid vortex; and collecting the one or more jets of thepoly-paraphenylene terephthalamide in the air gap of the liquid vortexand subsequently in the liquid of the liquid vortex of the collectiondevice to cause formation of the one or more micron, submicron ornanometer dimension poly-paraphenylene terephthalamide fibers, whereinthe liquid is water.

In another aspect, the present invention provides methods forfabricating a sheet of poly-paraphenylene terephthalamide nanofibers.The methods include providing a poly-paraphenylene terephthalamidesolution; rotating the poly-paraphenylene terephthalamide solution aboutan axis of rotation to cause ejection of the poly-paraphenyleneterephthalamide solution in one or more jets; generating a liquid vortexin a collection device for collecting the one or more jets of thepoly-paraphenylene terephthalamide, the liquid vortex including acentral air gap; and collecting the jets of the poly-paraphenyleneterephthalamide in the collection device, wherein the one or more jetsare initially ejected through the air gap of the liquid vortex andsubsequently through the liquid in the liquid vortex of the collectiondevice; wherein the ejection of the poly-paraphenylene terephthalamideinto the air gap and subsequently into the liquid in the collectiondevice causes formation of a sheet of micron, submicron or nanometerdimension poly-paraphenylene terephthalamide fibers, wherein the liquidis water.

In another aspect, the present invention provides methods forfabricating a sheet of poly-paraphenylene terephthalamide nanofibers.The methods include providing a device of the invention using the firstmotion generator to rotate the reservoir about an axis of rotation tocause ejection of the poly-paraphenylene terephthalamide in jets; usingthe second motion generator to rotate the liquid in the collectiondevice to generate the liquid vortex; and collecting the jets of thepoly-paraphenylene terephthalamide in the air gap of the liquid vortexand subsequently in the liquid of the liquid vortex of the collectiondevice to cause formation of the one or more micron, submicron ornanometer dimension poly-paraphenylene terephthalamide fibers, whereinthe liquid is water.

In one aspect, the present invention provides poly-paraphenyleneterephthalamide nanofibers and sheets prepared according to the methodsof the invention.

In one aspect, the present invention provides poly-paraphenyleneterephthalamide nanofibers and sheet prepared using the device of theinvention.

In one aspect, the present invention provides textiles comprising apoly-paraphenylene terephthalamide nanofiber or poly-paraphenyleneterephthalamide sheet prepared according to the methods of theinvention.

In one embodiment, the sheets of poly-paraphenylene terephthalamidenanofibers have a spacing between individual fibers of about 300 toabout 1000 nm.

In another embodiment, the average diameter of a nanofiber in a sheet ofpoly-paraphenylene terephthalamide nanofibers, comprising has an averagediameter of about 0.5 to about 5 μm.

In another embodiment, the sheets of poly-paraphenylene terephthalamidenanofibers have a thickness of about 0.1 to about 100 cm.

In another aspect, the present invention provides a personal protectiondevice, e.g., a bulletproof and/or a bladeproof vest, an athletic wear,e.g., a glove, a shirt, which is made using the foregoingpoly-paraphenylene terephthalamide nanofibers and sheets.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects, aspects, features, and advantages ofexemplary embodiments will become more apparent and may be betterunderstood by referring to the following description taken inconjunction with the accompanying drawings, in which:

FIG. 1 illustrates an exemplary fiber formation device for formingmicron, submicron or nanometer dimension polymeric fibers.

FIG. 2 is a flowchart illustrating an exemplary method for providing anexemplary fiber formation device.

FIG. 3 is a flowchart illustrating an exemplary method for using anexemplary fiber formation device.

FIGS. 4A-4F illustrate isotropic and anisotropic deoxyribonucleic acidfibers fabricated using exemplary fiber formation devices and methods. A5% DNA solution was prepared in a 30% ethanol solution, rotated at16,000 rpm into a 95% ethanol solution within the collection device.

FIG. 4A depicts an exemplary fiber formation device and exemplaryisotropic and anisotropic deoxyribonucleic acid fibers fabricated usingsuch a device.

FIG. 4B is a photomicrograph of exemplary deoxyribonucleic acid fibersthat were fabricated using the exemplary fiber formation device depictedin FIG. 4A by rotating a 5% DNA solution prepared in a 30% ethanolsolution at 16,000 rpm into a 95% ethanol solution within the collectiondevice.

FIG. 4C is a photomicrograph of exemplary deoxyribonucleic acid fibersthat were fabricated using the exemplary fiber formation device depictedin FIG. 4A by rotating a 5% DNA solution prepared in a 30% ethanolsolution at 16,000 rpm into a 95% ethanol solution within the collectiondevice.

FIG. 4D is a photomicrograph of exemplary deoxyribonucleic acid fibersthat were fabricated using the exemplary fiber formation device depictedin FIG. 4A by rotating a 5% DNA solution prepared in a 30% ethanolsolution at 16,000 rpm into a 95% ethanol solution within the collectiondevice.

FIG. 4E is a photomicrograph of exemplary deoxyribonucleic acid fibersthat were fabricated using the exemplary fiber formation device depictedin FIG. 4A by rotating a 5% DNA solution prepared in a 30% ethanolsolution at 16,000 rpm into a 95% ethanol solution within the collectiondevice.

FIG. 4F is a photomicrograph of exemplary deoxyribonucleic acid fibersthat were fabricated using the exemplary fiber formation device depictedin FIG. 4A by rotating a 5% DNA solution prepared in a 30% ethanolsolution at 16,000 rpm into a 95% ethanol solution within the collectiondevice.

FIGS. 5A-5E illustrate an exemplary method for the fabrication ofpolymeric fibers from a solution of deoxyribonucleic acid (DNA). Asolution of 5% DNA dissolved in a 7:3 mixture of water:ethanol, wasrotated at 16,000 rpm into a 95% ethanol solution within the collectiondevice.

FIG. 5A depicts placing a motor into a bath in the collection device.

FIG. 5B depicts spinning the motor.

FIG. 5C depicts extruding fibers.

FIG. 5D depicts collected fibers.

FIG. 5E depicts high-speed still images of the reservoir, solution andfibers.

FIG. 6A is a macroscopic images of DNA nanofibers produced by exemplarydevices and methods before alignment.

FIG. 6B is a macroscopic images of alginate nanofibers produced byexemplary devices and methods before alignment.

FIG. 7A is a scanning electron micrograph (SEM) image of DNA nanofibers.

FIG. 7B is a scanning electron micrograph (SEM) image of and alginatenanofibers.

For FIGS. 6A, 6B, 7A, and 7B, the DNA nanofibers were fabricated using asolution of 5% DNA dissolved in a 7:3 mixture of water:ethanol androtating at 16,000 rpm into a 95% ethanol solution within the collectiondevice and the alginate nanofibers were fabricated using a 5% alginatesolution prepared in water and rotating at 80,000 rpm into a solution of1% CaCl₂ within the collection device.

FIG. 8 illustrates an exemplary fiber formation device for formingmicron, submicron or nanometer dimension polymeric fibers.

FIG. 9 depicts the generation of a liquid vortex including an air gap inthe collection device of an exemplary fiber formation device illustratedin FIG. 8 for forming micron, submicron or nanometer dimension polymericfibers.

FIGS. 10A-10E are scanning electron micrographs (SEM) images ofpoly-paraphenylene terephthalamide nanofibers produced by exemplarydevices and methods of the invention.

FIG. 10A is a scanning electron micrograph (SEM) image ofpoly-paraphenylene terephthalamide nanofibers produced by exemplarydevices and methods of the invention.

FIG. 10B is a scanning electron micrograph (SEM) image ofpoly-paraphenylene terephthalamide nanofibers produced by exemplarydevices and methods of the invention.

FIG. 10C is a scanning electron micrograph (SEM) image ofpoly-paraphenylene terephthalamide nanofibers produced by exemplarydevices and methods of the invention.

FIG. 10D is a scanning electron micrograph (SEM) image ofpoly-paraphenylene terephthalamide nanofibers produced by exemplarydevices and methods of the invention.

FIG. 10E is a scanning electron micrograph (SEM) image ofpoly-paraphenylene terephthalamide nanofibers produced by exemplarydevices and methods of the invention.

FIG. 11A is an image of a poly-paraphenylene terephthalamide fabric fromDuPont and a poly-paraphenylene terephthalamide nanofiber sheet producedby exemplary devices and methods of the invention.

FIG. 11B is an image of a poly-paraphenylene terephthalamide fabric fromDuPont (left) and a poly-paraphenylene terephthalamide nanofiber sheetproduced by exemplary devices and methods of the invention (right).

FIG. 11C is an image of a poly-paraphenylene terephthalamide fabric fromDuPont following a puncture test.

FIG. 11D is an image of a poly-paraphenylene terephthalamide nanofibersheet produced by exemplary devices and methods of the inventionfollowing a puncture test.

FIG. 11E is an image of a poly-paraphenylene terephthalamide fabric fromDuPont depicting the weave of the fibers.

FIG. 11F is an image of a poly-paraphenylene terephthalamide fabric fromDuPont depicting the weave of the fibers.

DETAILED DESCRIPTION

Although devices and methods for the production of polymeric fibersemploying rotational motion have been previously described (see, e.g.,U.S. Patent Publication No. U.S. 2012/0135448 and PCT Publication No. WO2012/068402), fabrication of polymeric fibers using water solublepolymers and/or polymer solutions which require on-contact crosslinkingand/or precipitation to form physically and chemically stable polymericfibers remains challenging.

For example, until the present invention, it was challenging to formpolymeric fibers using polymers dissolved in slowly evaporatingsolvents, e.g., aqueous solvents, from polymers that require on-contactcross-linking (e.g., alginate) and/or from a polymer that cannot bereadily dissolved at a high enough concentrations to provide sufficientviscosity for random entanglement and solvent evaporation to formpolymeric fibers (e.g., deoxyribonucleic acid, polyurethane-polyureacopolymer, and polyacrylonitrile), and/or a polymer that requiresprecipitation (e.g., deoxyribonucleic acid), and/or a polymer dissolvedin water at low concentrations to form polymeric fibers, and/or apolymer that requires both extension in air and precipitation (e.g.,polyamides, e.g., liquid crystalline polymers, e.g., poly-paraphenyleneterephthalamide and poly(p-phenylene benzobisoxazole)).

Accordingly, the present invention solves these problems by providingdevices and methods which generally include extruding a polymer solutionthrough one or more orifices of a rotating reservoir into a liquid suchthat a polymeric fiber is solidified and formed upon contact with theliquid in the collection device. In some embodiments, the orifices ofthe reservoir may be completely or partially submerged in the liquid inthe collection device in order to eject the polymer from the reservoirdirectly into the liquid. In other embodiments, the orifices of thereservoir are positioned above the liquid in the collection device suchthat the polymer extruded from the orifice contacts air prior tocontacting the liquid in the collection device.

Exemplary embodiments provide improved systems, devices, and methods forforming micron, submicron or nanometer dimension polymeric fibers,without employing electrical fields, e.g., a high voltage electricalfield, to form the polymeric fibers.

Exemplary embodiments employ centrifugal or rotational motion impartedto a reservoir of polymer to eject the polymer through one or moreorifices in the reservoir. In some embodiments, the polymer is ejecteddirectly into a liquid held in a collection device for solidificationand formation of the polymeric fibers. In other embodiments, the polymeris ejected into an air gap generated by generating a liquid vortex inthe liquid in the collection device. In some embodiments, upon contactof the polymer with the liquid held in the collection device, theinteraction of the two materials causes precipitation and/orcross-linking of the polymer. Exemplary embodiments also enable tuningof the orientation, alignment and diameter of the polymeric fibers.

The terms “fiber” and “polymeric fiber” are used herein interchangeably,and both terms refer to fibers having micron, submicron, and nanometerdimensions. A “chemically and physically stable polymeric fiber” is onethat shows substantially no signs of, e.g., loss of strength measuredby, e.g., uniaxial tensile testing, and/or degradation rate in culturewith media or cells measured by, e.g., weight of the fibers over time.

Exemplary devices and methods may be used to form a single, continuouspolymeric fiber or a plurality of polymeric fibers of the same ordifferent diameters, e.g., diameters about 25 nanometers to about 50micrometers, about 100 nanometers to about 1 micrometer, about 500nanometers to about 100 micrometers, 25 micrometers to about 100micrometers, or about 5, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75,80, 85, 90, 95, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200,210, 220, 230, 240, 250, 260, 270, 280, 290, 300, 310, 320, 33, 340,350, 360, 370, 380, 390, 400, 410, 420, 430, 440, 450, 460, 470, 480,490, 500, 510, 520, 530, 540, 550, 560, 570, 580, 590, 600, 610, 620,630, 640, 650, 660, 670, 680, 690, 700, 710, 720, 730, 740, 750, 760,770, 780, 790, 800, 810, 820, 830, 840, 850, 860, 870, 880, 890, 900,910, 920, 930, 940, 950, 960, 970, 980, 990, 1000 nanometers, 10, 20,30, 40, or about 50 micrometers. Sizes and ranges intermediate to therecited diameters are also part of the invention.

The polymeric fibers formed using the methods and devices of theinvention may be of any length. In one embodiment, the length of thepolymeric fibers is dependent on the length of time the device is inmotion and/or the amount of polymer fed into the system. For example,the polymeric fibers may be about 1 nanometer, about 10 feet, or about500 yards. Additionally, the polymeric fibers may be cut to a desiredlength using any suitable instrument.

In one embodiment, the methods and device of the invention produce about0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or about 15 grams ofpolymeric fiber per hour.

In one embodiment of the invention, a plurality of micron, submicron ornanometer dimension polymeric fibers are formed. The plurality ofmicron, submicron or nanometer dimension polymeric fibers may be of thesame diameter or of different diameters.

In one embodiment, the methods of the invention result in thefabrication of a plurality of aligned (e.g., uniaxially aligned) micron,submicron or nanometer dimension polymeric fibers, e.g., a sheet ofpolymeric fibers.

The fibers produced according to the methods disclosed herein can be,for example, used as extracellular matrix and, together with cells, mayalso be used in forming engineered tissue. Such tissue is useful notonly for the production of prosthetic devices and regenerative medicine,but also for investigating tissue developmental biology and diseasepathology, as well as in drug discovery and toxicity testing. Thepolymeric fibers of the invention may also be combined with othersubstances, such as, therapeutic agents, in order to deliver suchsubstances to the site of application or implantation of the polymericfibers. The polymeric fibers produced according to the methods disclosedherein may also be used to generate food products, thread, fabrics,membranes and filters.

A. Exemplary Fiber Formation Devices

Exemplary embodiments provide systems, devices and methods for formingthree-dimensional micron, submicron and nanometer dimension fibers froma material solution by imparting rotational and/or linear motion to thematerial solution. In exemplary embodiment, the devices aresubstantially void of an electric field and do not require an electricalfield in order to generate the polymeric fiber. In some embodiments, thedevices are free of a needle.

Exemplary fiber formation devices and methods may be used to make fibersfrom a range of materials. Exemplary materials include polymers thatrequire on-contact cross-linking (e.g., alginate) and/or from a polymerthat cannot be readily dissolved at a high enough concentrations toprovide sufficient viscosity for random entanglement and solventevaporation to form polymeric fibers (e.g., deoxyribonucleic acid,polyurethane-polyurea copolymer, and polyacrylonitrile), and/or apolymer that requires precipitation (e.g., deoxyribonucleic acid),and/or a polymer dissolved in water at low concentrations to formpolymeric fibers, and/or a polymer that requires both extension in airand precipitation (e.g., polyamides, e.g., liquid crystalline polymers,e.g., poly-paraphenylene terephthalamide, and poly(p-phenylenebenzobisoxazole)).

Exemplary fiber formation devices may have many applications including,but not limited to, mass production of polymer fibers, production ofultra-aligned scaffolds, bio-functional scaffolds for in vitro tissueengineering applications, bio-functional scaffolds for in vivo tissueengineering applications, bio-functional suture threads, ultra-strongfiber and fabric production, bio-functional protein or polymer filters,protective clothing or coverings, etc.

In an exemplary fiber formation device 100 illustrated in FIG. 1, one ormore reservoirs 102 are provided for holding one or more materialsolutions (e.g., polymer in solution) for forming polymeric fibers. Thereservoir 102 may include one or more orifices or openings 104 forproviding an outlet to the material solution to the exterior of thereservoir 102. The fiber formation device 100 includes one or morecollection devices 106, e.g., a beaker, a tub, a plate, bobbin, a drum,etc., for collecting the fibers ejected through the orifice 104 of thereservoir 102. The collection device 106 may hold a liquid that enablesprecipitation and/or on-contact cross-linking of the polymeric fibersupon contact of the material solution with the liquid, for example,water, ethanol (e.g., about 30, 35, 40, 45, 50, 55, 60, 65, or about 70%ethanol), DMF (e.g., about 20, 25, 30, 35, 40, 45, or 50% DMF) calciumchloride, N-methyl-pyrrolidone and calcium chloride, sulfuric acid, andthe like.

In the exemplary embodiment illustrated in FIG. 1, the collection device106 and the reservoir 102 are configured and positioned so that theorifices 104 of the reservoir 102 are at least partially submerged inthe liquid in the collection device 106. The orifices 104 may besubmerged partially or completely in the liquid in the collection device106. In an exemplary embodiment, the collection device 106 is disposedvertically below the reservoir 102. The configuration of the exemplaryfiber formation device 100 creates a liquid-to-liquid interface at theorifices 104 between the material solution in the reservoir 102 and theliquid in the collection device 106. The liquid-to-liquid interface maybe free of ambient air in some embodiments. The liquid-to-liquidinterface at the orifices 104 causes the material solution ejected fromthe orifices 104 to directly enter the liquid held in the collectiondevice 106, which causes solidification and formation of one or moremicron, submicron or nanometer dimension polymeric fibers.

Although the exemplary collection device 106 illustrated in FIG. 1 isrepresented as being stationary, other exemplary collection devices maybe moving, e.g., rotating and/or oscillating. In some exemplaryembodiments, the velocity of the collection device 106, linear orrotational, may be kept substantially constant during a fiber formationsession or may be increased or decreased during a fiber formationsession. Exemplary linear velocities of the collection device 106 mayrange from about 5 m/s to about 40 m/s in some exemplary embodiments,but are not limited to this exemplary range.

The reservoir 102 may be coupled directly or indirectly to one or moremotion generators, e.g., a rotating motor, etc., that impart a motion tothe reservoir 102. The motion imparted to the reservoir 102 may beconfigured to impart sufficient shear force to the material solution inthe reservoir 102 for a sufficient time such that the material solutionis ejected or extruded from the reservoir 102, thereby forming one ormore micron, submicron or nanometer dimension polymeric fibers.Exemplary embodiments may use different combinations of motiongenerators to create and control desired weaves and/or alignments of thefibers formed by the motion of the reservoir 102.

In one embodiment, a motion generator may be used to impart a rotationalmotion to the reservoir 102 so that the reservoir 102 spins about acentral axis of rotation R. An exemplary rotational motion generator maybe provided in accordance with the disclosure of a rotational motiongenerator in U.S. Patent Publication No U.S. 2012/0135448 and PCTPublication No. WO 2012/068402, the entire contents of each of which areincorporated herein by reference.

In another embodiment, a motion generator may be used to impart a linearmotion to the reservoir 102 so that the reservoir 102 moves back andforth along the central axis R. In another embodiment, a motiongenerator may impart both a rotational motion and a linear motion to thereservoir 102. In other exemplary embodiments, the motion generator 110may impart other types of motions to the reservoir 102, e.g., irregularmotions, complex motion patterns, linear motion along different axes,rotational motion about different axes, motion that changes betweenlinear and rotational, etc.

The reservoir 102 may be coupled to the motion generator using one ormore mechanical coupling members, e.g., a rod, piston, etc., thatreliably and efficiently transfer the motion generated by the generatorto the reservoir 102. The motion generator may be coupled to anelectrical power source (not shown), e.g., electrical mains or one ormore batteries, that supplies electrical power to power the generator.

In operation, as the motion generator moves the reservoir 102 in arotational manner or back and forth in a linear manner, the inertia ofthe material solution in the reservoir 102 resists the motion of themotion generator and the reservoir 102. This causes the materialsolution to be pulled against one or more walls of the reservoir 102 andto be ejected or extruded through one or more orifices 104 that arepresent on the walls. The material solution forms one or more jets as itis pulled through the orifices 104. The jets exit the reservoir 102through the orifices 104 and enter the liquid held in the collectiondevice 106. The interaction of the material jets with the liquid causesformation and solidification of the micron, submicron or nanometerdimension polymeric fibers. In some cases, the interaction of thematerial jets with the liquid causes precipitation and/or on-contactcross-linking of the polymeric fibers.

In an alternative embodiment, the reservoir 102 may be pressurized toeject the polymer material from the reservoir through the one or moreorifices 104. For example, a mechanical pressurizer may be applied toone or more surfaces of the reservoir to decrease the volume of thereservoir, and thereby eject the material from the reservoir. In anotherexemplary embodiment, a fluid pressure may be introduced into thereservoir to pressurize the internal volume of the reservoir, andthereby eject the material from the reservoir.

In exemplary embodiments that employ motion, the velocity of thereservoir 102, linear or rotational, may be kept substantially constantduring a fiber formation session or may be increased or decreased duringa fiber formation session. Rotational speeds of the reservoir 102 inexemplary embodiments may range from about 1,000 rpm-400,000 rpm, forexample, about 1,000 rpm to about 40,000 rpm, about 1,000 rpm to about20,000 rpm, about 3,000 rpm-90,000 rpm, about 3,000 rpm-50,000 rpm,about 3,000 rpm-25,000 rpm, about 5,000 rpm-20,000 rpm, about 5,000 rpmto about 15,000 rpm, about 50,000 rpm to about 100,000 rpm, or about50,000 rpm to about 400,000 rpm, e.g., about 1,000, 1,500, 2,000, 2,500,3,000, 3,500, 4,000, 4,500, 5,000, 5,500, 6,000, 6,500, 7,000, 7,500,8,000, 8,500, 9,000, 9,500,10,000, 10,500, 11,000, 11,500, 12,000,12,500, 13,000, 13,500, 14,000, 14,500, 15,000, 15,500, 16,000, 16,500,17,000, 17,500, 18,000, 18,500, 19,000, 19,500, 20,000, 20,500, 21,000,21,500, 22,000, 22,500, 23,000, 23,500, 24,000, 32,000, 50,000, 55,000,60,000, 65,000, 70,000, 75,000, 80,000, 85,000, 90,000, 95,000, 100,000,105,000, 110,000, 115,000, 120,000, 125,000, 130,000, 135,000, 140,000,145,000, 150,000 rpm, about 200,000 rpm, 250,000 rpm, 300,000 rpm,350,000 rpm, or 400,000 rpm. Ranges and values intermediate to the aboverecited ranges and values are also contemplated to be part of theinvention.

In certain embodiments, rotating speeds of about 50,000 rpm-400,000 rpmare intended to be encompassed by the methods of the invention. In oneembodiment, devices employing rotational motion may be rotated at aspeed greater than about 50,000 rpm, greater than about 55,000 rpm,greater than about 60,000 rpm, greater than about 65,000 rpm, greaterthan about 70,000 rpm, greater than about 75,000 rpm, greater than about80,000 rpm, greater than about 85,000 rpm, greater than about 90,000rpm, greater than about 95,000 rpm, greater than about 100,000 rpm,greater than about 105,000 rpm, greater than about 110,000 rpm, greaterthan about 115,000 rpm, greater than about 120,000 rpm, greater thanabout 125,000 rpm, greater than about 130,000 rpm, greater than about135,000 rpm, greater than about 140,000 rpm, greater than about 145,000rpm, greater than about 150,000 rpm, greater than about 160,000 rpm,greater than about 165,000 rpm, greater than about 170,000 rpm, greaterthan about 175,000 rpm, greater than about 180,000 rpm, greater thanabout 185,000 rpm, greater than about 190,000 rpm, greater than about195,000 rpm, greater than about 200,000 rpm, greater than about 250,000rpm, greater than about 300,000 rpm, greater than about 350,000 rpm, orgreater than about 400,000 rpm.

Exemplary devices employing rotational motion may be rotated for a timesufficient to form a desired polymeric fiber, such as, for example,about 1 minute to about 100 minutes, about 1 minute to about 60 minutes,about 10 minutes to about 60 minutes, about 30 minutes to about 60minutes, about 1 minute to about 30 minutes, about 20 minutes to about50 minutes, about 5 minutes to about 20 minutes, about 5 minutes toabout 30 minutes, or about 15 minutes to about 30 minutes, about 5-100minutes, about 10-100 minutes, about 20-100 minutes, about 30-100minutes, or about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16,17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34,35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52,53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70,71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88,89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100 minutes, or more. Timesand ranges intermediate to the above-recited values are also intended tobe part of this invention.

In embodiments that employ linear motion, linear speeds of the reservoir102 may range from about 0.0001 m/s to about 4.2 m/s, but are notlimited to this exemplary range. Comparing some exemplary devices thatemploy purely linear motion to some exemplary devices that employ purelyrotational motion for fiber formation, a linear velocity of about 10.8m/s corresponds to about 8,000 rpm of rotational velocity, a linearvelocity of about 16.2 m/s corresponds to about 12,000 rpm of rotationalvelocity, and a linear velocity of about 27.1 m/s corresponds to about20,000 rpm of rotational velocity.

An exemplary reservoir 102 may have a volume ranging from about onenanoliter to about 1 milliliter, about one nanoliter to about 5milliliters, about 1 nanoliter to about 100 milliliters, or about onemicroliter to about 100 milliliters, for holding the liquid material.Some exemplary volumes include, but are not limited to, about onenanoliter o about 1 milliliter, about one nanoliter to about 5milliliters, about 1 nanoliter to about 100 milliliters, one microliterto about 100 microliters, about 1 milliliter to about 20 milliliters,about 20 milliliters to about 40 milliliters, about 40 milliliters toabout 60 milliliters, about 60 milliliters to about 80 milliliters,about 80 milliliters to about 100 milliliters, but are not limited tothese exemplary ranges. Exemplary volumes intermediate to the recitedvolumes are also part of the invention. In certain embodiment, thevolume of the reservoir is less than about 5, less than about 4, lessthan about 3, less than about 2, or less than about 1 milliliter. Inother embodiments, the physical size of an unfolded polymer and thedesired number of polymers that will form a fiber dictate the smallestvolume of the reservoir.

In some embodiments, the reservoir 102 may include one or more inletports, each coupled to one or more inlet pipes for introducing one ormore material solutions and/or one or more other fluids (e.g., airpressure) into the reservoir 102. An exemplary inlet pipe may be coupledto one or more storage devices that store a material solution or to oneor more devices that produce a material solution. One or more materialsolutions may be fed into the reservoir 102 through the inlet port at aconstant flow rate or at variable flow rates. In an exemplaryembodiment, the inlet port may be closed temporarily or permanentlyafter the reservoir 102 is filled before fiber formation. In anotherexemplary embodiment, the inlet port may remain open for continuous orintermittent filling of the reservoir 102 during fiber formation. In anexemplary embodiment, the reservoir 102 may be pre-filled and the filledreservoir 102 may not include the inlet pipe and may have one or moretemporarily or permanently sealed inlet ports. In another exemplaryembodiment, the inlet port may remain coupled to the inlet pipe and thereservoir 102 may be filled continuously or in one or more sessionsduring fiber formation.

Exemplary orifices 104 may have any suitable cross-sectional geometryincluding, but not limited to, circular (as illustrated in the exemplaryembodiment of FIG. 1), oval, square, rectangular, etc. In an exemplaryembodiment, one or more nozzles may be provided associated with anexemplary orifice 104 to provide control over one or morecharacteristics of the material solution exiting the reservoir 102through the orifice including, but not limited to, the flow rate, speed,direction, mass, shape and/or pressure of the material solution. Thelocations, cross-sectional geometries and arrangements of the orifices104 on the reservoir 102, and/or the locations, cross-sectionalgeometries and arrangements of the nozzles on the orifices 104, may beconfigured based on the desired characteristics of the resulting fibersand/or based on one or more other factors including, but not limited to,viscosity of the material solution, the rate of solvent evaporationduring fiber formation, etc.

Exemplary orifice lengths that may be used in some exemplary embodimentsrange between about 0.001 m and about 0.1 m, between about 0.001 m andabout 0.01 m, between about 0.001 m and about 0.005 m, between about0.002 m and about 0.005 m, between about 0.001 m and about 0.05 m,between about 0.0015 m and about 0.007 m, between about 0.002 m andabout 0.007 m, between about 0.0025 m and about 0.0065 m, between about0.002 m and about 0.006 m, e.g., about 0.0015, 0.002, 0.0025, 0.003,0.0035, 0.004, 0.0045, 0.005, 0.0055, 0.006, 0.0065, 0.007, 0.0075,0.008, 0.0085, 0.009, 0.0095, 0.01, 0.015, 0.02, 0.025, 0.03, 0.035,0.04, 0.045, 0.05, 0.055, 0.06, 0.065, 0.07, 0.075, 0.08, 0.085, 0.09,0.095, or 0.1 m. Ranges and values intermediate to the above recitedranges and values are also contemplated to be part of the invention.

Exemplary orifice diameters that may be used in some exemplaryembodiments range between about 0.05 μm and about 1000 μm, e.g., betweenabout 0.05 and about 500, between about 0.05 and 100, between about 0.1and 1000, between about 0.1 and 500, between about 0.1 and 100, betweenabout 1 and 1000, between about 1 and 500, between about 1 and 100,between about 10 and 1000, between about 10 and 500, between about 10and 100, between about 50 and 1000, between about 50 and 500, betweenabout 50 and 100, between about 100 and 1000, between about 100 and 500,between about 150 and 500, between about 200 and 500, between about 250and 500, between about 250 and 450, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1,0.15, 0.2, 0.225, 0.25, 0.275, 0.3, 0.325, 0.35, 0.375, 0.4, 0.425,0.45, 0.475, 0.5, 0.525, 0.55, 0.575, 0.6, 0.625, 0.65, 0.675, 0.7,0.725, 0.75, 0.075, 0.8, 0.825, 0.85, 0.825, 0.9, 0.925, 0.95, 0.975,1.0, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9,9.5, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 150, 200, 250, 300, 350,400, 450, 500, 550, 600, 650, 700, 750, 800, 850, 900, 950, or 1000 μm.Ranges and values intermediate to the above recited ranges and valuesare also contemplated to be part of the invention.

The reservoir and collection device may be constructed of any material,e.g., a material that can withstand heat and/or that is not sensitive tochemical organic solvents. In one embodiment, the reservoir and thecollection device are made up of glass or a plastic material, e.g.,polypropylene, polyethylene, or polytetrafluoroethylene. In anotherembodiment, the reservoir and the collection device are made up of ametal, e.g., aluminum, steel, stainless steel, tungsten carbide,tungsten alloys, titanium or nickel.

Any suitable size or geometrically shaped reservoir or collector may beused in the devices of the invention. For example, the reservoir and/orcollector may be round, rectangular, or oval. The reservoir and/orcollector may be round, oval, rectangular, or a half-heart shape. Thecollector may also be shaped in the form of any living organ, such as aheart, kidney, liver lobe(s), bladder, uterus, intestine, skeletalmuscle, or lung shape, or portion thereof. The collector may further beshaped as any hollow cavity, organ or tissue, such as a circular musclestructure, e.g., a sphincter or iris, or, for the fabrication ofprotective clothing, a human head, a torso, a hand, etc. These shapesallow the polymeric fibers to be deposited in the form of a living organfor the production of engineered tissue and organs, described in moredetail below, or as a glove, a helmet, a vest, or a shirt.

In one embodiment, the devices of the invention further comprise acomponent suitable for continuously feeding the polymer into therotating reservoir, such as a spout or syringe pump

The reservoir may also include a heating element for heating and/ormelting the polymer.

In certain embodiments, the collection device is maintained at aboutroom temperature, e.g., about 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, orabout 30° C. and ambient humidity, e.g., about 30, 31, 32, 33, 34, 35,36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53,54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71,72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89,or about 90% humidity. The devices may be maintained at and the methodsmay be formed at any suitable temperature and humidity.

In one embodiment of the invention, the device is free of a needle.

In one embodiment, the formed micron, submicron or nanometer dimensionpolymeric fiber is imaged, e.g., using a scanning electron microscope.

Exemplary fiber formation devices may employ one or more mechanisms tocontrol the force and/or speed with which the material jet leaves thereservoir through one or more orifices. In an exemplary embodiment, thespeed (linear and/or rotational) and/or magnitude of the motion (e.g.,the distance traveled by the motion generator along a linear axis) ofthe motion generator may be increased to increase the pressure of thematerial solution in the reservoir which, in turn, increases the forceand/or the speed with which the jets leave the reservoir, and viceversa. In an exemplary embodiment, the material solution may be fed intothe reservoir through an inlet port during fiber formation to increasethe pressure of the material solution in the reservoir which, in turn,increases the force and/or the speed with which the jets leave thereservoir, and vice versa. In an exemplary embodiment, the materialsolution may be fed into the reservoir through the inlet port at afaster or a slower rate to increase or decrease, respectively, thepressure of the material solution in the reservoir. This, in turn,raises or lowers, respectively, the force and/or the speed with whichthe jets leave the reservoir.

Exemplary fiber formation devices may employ the controllable linearmotion of the reservoir to control alignment of the resulting fibers.Controlling one or more aspects of the linear motion of an exemplaryreservoir enables control over the deposition and alignment of eachlayer of polymeric fibers onto the collection device. Exemplary aspectsof the linear motion that may be controlled in exemplary devicesinclude, but are not limited to, the speed of the linear motion of thereservoir, the force and/or speed with which the material jet leaves thereservoir, the dimensions of the reservoir, etc.

In some exemplary embodiments, the speed with which an exemplary motiongenerator oscillates the reservoir and/or the collection device affectsthe pitch of the helical fibers and the spacing between the fibers. Anincreasing vertical speed of the reservoir and/or the collection devicetypically results in an increased pitch of the helical fibers.Accordingly, in an exemplary embodiment, the pitch of the fibers formedis increased by increasing the linear speed of the oscillating reservoirand/or the oscillating collection device along the vertical direction,and vice versa. An increasing vertical speed of the reservoir and/or thecollection device typically results in an increased spacing between thefibers. Accordingly, in an exemplary embodiment, the fiber spacingformed is increased by increasing the linear speed of the oscillatingreservoir and/or the oscillating collection device along the verticaldirection, and vice versa.

In some exemplary embodiments, the polymeric fiber configuration formedon the collection device in exemplary devices of the invention, e.g., amat configuration, a mesh configuration, etc., may be controlled bycontrolling aspects of the linear motion of the reservoir and/or thecollection device. In some exemplary embodiments, the pore sizes formedbetween fibers of a mesh configuration, e.g., larger or smaller poresizes, may be controlled by controlling aspects of the linear motion ofthe reservoir and/or the collection device in exemplary devices. Anincreasing vertical speed of the reservoir and/or collection devicetypically results in larger pore sizes of the fibers, and vice versa.Accordingly, in an exemplary embodiment, the pore sizes of a polymericfiber mesh structure formed is increased by increasing the linear speedof the oscillating reservoir and/or oscillating collection device alongthe vertical direction, and vice versa. Thus, exemplary devices may beused to form fibers of different porosities, e.g., for filters withvarying pore sizes, for a cell-scaffold with a desired pore size whichmay be used to select a desired cell-scaffold infiltration, etc.

In an exemplary embodiment, as the reservoir and/or the collectiondevice is oscillated in a linear manner while the reservoir is beingrotated, the fibers are deposited in a controlled mesh structure,wherein the linear velocity of the reservoir and/or collection devicedetermines the mesh pore size and the pitch of the polymeric fiber meshstructure. The pore size depends on the fiber diameter as well as thefiber pitch. A maximum pore size typically results from large fibers andan approximately 45 degree pitch in one direction. In this exemplaryembodiment, fibers exiting the orifices of the reservoir at anapproximately 45 degree angle in one direction are deposited in anapproximately −45 degree angle in the other direction due to the linearmotion. This results in the formation of layers of fibers that overlapeach other at approximately 90 degrees.

In another exemplary fiber formation device 800 illustrated in FIG. 8,one or more reservoirs 802 are provided for holding one or more materialsolutions (e.g., polymer in solution) for forming polymeric fibers. Thereservoir 802 may include one or more orifices or openings 804 forproviding an outlet to the material solution to the exterior of thereservoir 802. The fiber formation device 800 includes one or morecollection devices 806, e.g., a plate, bobbin, etc., for collecting thefibers ejected through the orifice 804 of the reservoir 102. Thecollection device 806 may hold a liquid that enables precipitationand/or on-contact cross-linking of the polymeric fibers upon contact ofthe material solution with the liquid, for example, water, ethanol(e.g., about 30, 35, 40, 45, 50, 55, 60, 65, or about 70% ethanol), DMF(e.g., about 20, 25, 30, 35, 40, 45, or about 50% DMF) calcium chloride,N-methyl-pyrrolidone and calcium chloride, sulfuric acid, and the like.

The exemplary device illustrated in FIG. 8 includes a motion generator808 couplable (e.g., directly or indirectly) to the collection device.The motion generator 808 is configured to impart rotational motion tothe liquid in the collection device to generate a liquid vortexincluding an air gap 810 which is essentially positioned centrally inthe liquid vortex in the collection device. The reservoir 802 and thecollection device 806 are configured and positioned such that the one ormore orifices 804 of the reservoir are not in contact (e.g., not incontact either partially or completely) with the liquid in thecollection device 806 but are, rather configured and positioned in theair gap 810 of the liquid vortex in the collection device. In general,the air gap 810 is formed along a central axis of the liquid vortex andabuts the top surface of the liquid in the liquid vortex such that theone or more orifices 804 of the reservoir 802 are positioned below thehighest level of the top surface of the liquid in the collection device806. In exemplary embodiments, the one or more orifices 804 arehorizontally spaced from the liquid vortex by a distance of betweenabout 0.1-8.0 cm, between about 1-8.0 cm, between about 1.5-7.5 cm,between about 2.0-7.0 cm, between about 2.5-6.5 cm, between about2.5-6.0 cm, between about 2.5-5.5 cm, between about 2.5-5.0 cm, betweenabout 3.0-6.0 cm, between about 3.0-5.5 cm, between about 3.0-5.0 cm,e.g., about 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2,1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 3.5, 2.6,2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0,4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 5.0, 5.1, 5.2, 5.3, 5.4,5.5, 5.6, 5.7, 5.8, 5.9, 6.0, 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8,6.9, 7.0, 7.1, 7.2, 7.3, 7.5, 7.5, 7.6, 7.7, 7.8, 7.9, or about 8.0 cm.Ranges and values intermediate to the above recited ranges and valuesare also contemplated to be part of the invention. Ejection of thepolymer into the air gap extends the fibers and alignment and subsequentcontact with the liquid of the liquid vortex in the collection device806 causes precipitation or cross-linking or formation of one or moremicron, submicron or nanometer dimension polymeric fibers. In anexemplary embodiment, the collection device 806 is disposed verticallybelow the reservoir 802.

The motion generator 808 may further comprise one or more of a motor,one or more magnets, and a heating element for heating the liquid in thecollection device 806. The speed of the motion generator 808 may becontrollable and used to generate rotational motion of the liquid in thecollection device at about 200-1,500 rpm, about 250-1,500 rpm, about300-1,500 rpm, about 300-1,250 rpm, about 200-1,250 rpm, about 200-500rpm, about 250-500 rpm, about 200-450 rpm, about 250-450 rpm, about900-1,300 rpm about 950-1,300 rpm, about 900-1,200 rpm, about 950-1,200rpm, about 900-1,250 rpm, about 950-1,250 rpm, about 1,000-1,200 rpm, orabout 200, 250, 300, 350, 400, 450, 500 550, 600 650, 700, 750, 800,850, 900, 950, 1,000, 1,050, 1,100, 1,150, 1,200, 1,250, 1,300, 1,350,1,400, 1,450, or about 1,500 rpm. Ranges and values intermediate to theabove recited ranges and values are also contemplated to be part of theinvention. The size of, e.g., the collection device, the volume ofliquid, and the size of a magnet, will dictate the speed of the motiongenerator necessary to provide an appropriate distance between ahorizontally spaced orifice and the liquid vortex.

The motion generator 808 may comprise a drainage system that imparts therotational motion to the liquid by draining the liquid through thedraining system. A drainage system may be configured in the collectiondevice 806 and couplable to a fluid inlet and a fluid outlet to controlflow rate of the liquid in the collection device. The drainage system isconfigured so a liquid vortex is generated by drainage of the drainagesystem. The drainage system is controllable to control the flow ratethrough the drainage system and to control the flow rate through thefluid inlet and fluid outlet.

The reservoir 802 may be coupled directly or indirectly to one or moremotion generator 812, e.g., a rotating motor, etc., that impart a motionto the reservoir 802. The motion imparted to the reservoir 802 may beconfigured to impart sufficient shear force to the material solution inthe reservoir 802 for a sufficient time such that the material solutionis ejected or extruded from the reservoir 802, thereby forming one ormore micron, submicron or nanometer dimension polymeric fibers.Exemplary embodiments may use different combinations of motiongenerators to create and control desired weaves and/or alignments of thefibers formed by the motion of the reservoir 802.

In one embodiment, a motion generator 812 may be used to impart arotational motion to the reservoir 802 so that the reservoir 802 spinsabout a central axis of rotation R. An exemplary rotational motiongenerator 812 may be provided in accordance with the disclosure of arotational motion generator in U.S. Patent Publication No U.S.2012/0135448 and PCT Publication No. WO 2012/068402, the entire contentsof each of which are incorporated herein by reference. The motiongenerators 808 and 812 may impart rotational motion in the same oropposite rotational direction.

In another embodiment, a motion generator 812 may be used to impart alinear motion to the reservoir 802 so that the reservoir 802 moves backand forth along the central axis R. In another embodiment, a motiongenerator 812 may impart both a rotational motion and a linear motion tothe reservoir 802. In other exemplary embodiments, the motion generator812 may impart other types of motions to the reservoir 802, e.g.,irregular motions, complex motion patterns, linear motion alongdifferent axes, rotational motion about different axes, motion thatchanges between linear and rotational, etc.

The reservoir 802 may be coupled to the motion generators 812 using oneor more mechanical coupling members, e.g., a rod, piston, etc., thatreliably and efficiently transfer the motion generated by the generatorto the reservoir 802.

The motion generator 808 and/or 812 may be coupled to an electricalpower source (not shown), e.g., electrical mains or one or morebatteries, that supplies electrical power to power the generator.

In operation, as the motion generator 812 moves the reservoir 802 in arotational manner or back and forth in a linear manner, the inertia ofthe material solution in the reservoir 802 resists the motion of themotion generator 812 and the reservoir 802. This causes the materialsolution to be pulled against one or more walls of the reservoir 802 andto be ejected or extruded through one or more orifices 804 that arepresent on the walls. The material solution forms one or more jets as itis pulled through the orifices 804. The jets exit the reservoir 802through the orifices 804 and enters the air gap 810 which permits highextensional shear of the polymer exiting the orifice prior to contactingthe liquid in the collection device 806. The subsequent interaction ofthe material elongated in the air gap 810 with the liquid causesformation and solidification of the micron, submicron or nanometerdimension polymeric fibers. In some cases, the interaction of thematerial jets with the liquid causes precipitation and/or on-contactcross-linking of the polymeric fibers.

In an alternative embodiment, the reservoir 802 may be pressurized toeject the polymer material from the reservoir through the one or moreorifices 804. For example, a mechanical pressurizer may be applied toone or more surfaces of the reservoir to decrease the volume of thereservoir, and thereby eject the material from the reservoir. In anotherexemplary embodiment, a fluid pressure may be introduced into thereservoir to pressurize the internal volume of the reservoir, andthereby eject the material from the reservoir.

In exemplary embodiments that employ motion, the velocity of thereservoir 802, linear or rotational, may be kept substantially constantduring a fiber formation session or may be increased or decreased duringa fiber formation session. Rotational speeds of the reservoir 802 inexemplary embodiments may range from about 1,000 rpm-400,000 rpm, forexample, about 1,000 rpm to about 40,000 rpm, about 1,000 rpm to about20,000 rpm, about 3,000 rpm-85,000 rpm, about 3,000 rpm-50,000 rpm,about 3,000 rpm-25,000 rpm, about 5,000 rpm-20,000 rpm, about 5,000 rpmto about 15,000 rpm, or about 50,000 rpm to about 400,000 rpm, e.g.,about 1,000, 1,500, 2,000, 2,500, 3,000, 3,500, 4,000, 4,500, 5,000,5,500, 6,000, 6,500, 7,000, 7,500, 8,000, 8,500, 9,000, 9,500, 10,000,10,500, 11,000, 11,500, 12,000, 12,500, 13,000, 13,500, 14,000, 14,500,15,000, 15,500, 16,000, 16,500, 17,000, 17,500, 18,000, 18,500, 19,000,19,500, 20,000, 20,500, 21,000, 21,500, 22,000, 22,500, 23,000, 23,500,24,000, 32,000, 50,000, 55,000, 60,000, 65,000, 70,000, 75,000, 80,000,85,000, 90,000, 95,000, 100,000, 105,000, 110,000, 115,000, 120,000,125,000, 130,000, 135,000, 140,000, 145,000, 150,000 rpm, about 200,000rpm, 250,000 rpm, 300,000 rpm, 350,000 rpm, or 400,000 rpm. Ranges andvalues intermediate to the above recited ranges and values are alsocontemplated to be part of the invention.

In certain embodiments, rotating speeds of about 50,000 rpm-100,000 rpmor about 50,000 rpm-400,000 rpm are intended to be encompassed by themethods of the invention. In one embodiment, devices employingrotational motion may be rotated at a speed greater than about 50,000rpm, greater than about 55,000 rpm, greater than about 60,000 rpm,greater than about 65,000 rpm, greater than about 70,000 rpm, greaterthan about 75,000 rpm, greater than about 80,000 rpm, greater than about85,000 rpm, greater than about 90,000 rpm, greater than about 95,000rpm, greater than about 100,000 rpm, greater than about 105,000 rpm,greater than about 110,000 rpm, greater than about 115,000 rpm, greaterthan about 120,000 rpm, greater than about 125,000 rpm, greater thanabout 130,000 rpm, greater than about 135,000 rpm, greater than about140,000 rpm, greater than about 145,000 rpm, greater than about 150,000rpm, greater than about 160,000 rpm, greater than about 165,000 rpm,greater than about 170,000 rpm, greater than about 175,000 rpm, greaterthan about 180,000 rpm, greater than about 185,000 rpm, greater thanabout 190,000 rpm, greater than about 195,000 rpm, greater than about200,000 rpm, greater than about 250,000 rpm, greater than about 300,000rpm, greater than about 350,000 rpm, or greater than about 400,000 rpm.

Exemplary devices employing rotational motion may be rotated for anydesired period of time, such as a time sufficient to form a desiredlength of polymeric fiber or desired collection of polymeric fibers(e.g., a sheet of polymeric fibers having a desired size and shape andwhich are held together by fiber-to-fiber interactions), such as, forexample, about 1 minute to about 100 minutes, about 1 minute to about 60minutes, about 10 minutes to about 60 minutes, about 30 minutes to about60 minutes, about 1 minute to about 30 minutes, about 20 minutes toabout 50 minutes, about 5 minutes to about 20 minutes, about 5 minutesto about 30 minutes, or about 15 minutes to about 30 minutes, about5-100 minutes, about 10-100 minutes, about 20-100 minutes, about 30-100minutes, or about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16,17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34,35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52,53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70,71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88,89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100 minutes, or more. Timesand ranges intermediate to the above-recited values are also intended tobe part of this invention.

In embodiments that employ linear motion, linear speeds of the reservoir802 may range from about 0.0001 m/s to about 4.2 m/s, but are notlimited to this exemplary range. Comparing some exemplary devices thatemploy purely linear motion to some exemplary devices that employ purelyrotational motion for fiber formation, a linear velocity of about 10.8m/s corresponds to about 8,000 rpm of rotational velocity, a linearvelocity of about 16.2 m/s corresponds to about 12,000 rpm of rotationalvelocity, and a linear velocity of about 27.1 m/s corresponds to about20,000 rpm of rotational velocity.

An exemplary reservoir 802 may have any suitable volume, such as, forexample, a volume ranging from about one nanoliter to about 1milliliter, about one nanoliter to about 5 milliliters, about 1nanoliter to about 100 milliliters, or about one microliter to about 100milliliters, for holding the liquid material. Some exemplary volumesinclude, but are not limited to, about one nanoliter o about 1milliliter, about one nanoliter to about 5 milliliters, about 1nanoliter to about 100 milliliters, one microliter to about 100microliters, about 1 milliliter to about 20 milliliters, about 20milliliters to about 40 milliliters, about 40 milliliters to about 60milliliters, about 60 milliliters to about 80 milliliters, about 80milliliters to about 100 milliliters, but are not limited to theseexemplary ranges. Exemplary volumes intermediate to the recited volumesare also part of the invention. In certain embodiment, the volume of thereservoir is less than about 5, less than about 4, less than about 3,less than about 2, or less than about 1 milliliter. In otherembodiments, the physical size of an unfolded polymer and the desirednumber of polymers that will form a fiber dictate the smallest volume ofthe reservoir.

In some embodiments, the reservoir 802 may include one or more inletports, each coupled to one or more inlet pipes for introducing one ormore material solutions and/or one or more other fluids (e.g., airpressure) into the reservoir 802. An exemplary inlet pipe may be coupledto one or more storage devices that store a material solution or to oneor more devices that produce a material solution. One or more materialsolutions may be fed into the reservoir 802 through the inlet port at aconstant flow rate or at variable flow rates. In an exemplaryembodiment, the inlet port may be closed temporarily or permanentlyafter the reservoir 802 is filled before fiber formation. In anotherexemplary embodiment, the inlet port may remain open for continuous orintermittent filling of the reservoir 802 during fiber formation. In anexemplary embodiment, the reservoir 802 may be pre-filled and the filledreservoir 802 may not include the inlet pipe and may have one or moretemporarily or permanently sealed inlet ports. In another exemplaryembodiment, the inlet port may remain coupled to the inlet pipe and thereservoir 802 may be filled continuously or in one or more sessionsduring fiber formation.

Exemplary orifices 804 may have any suitable cross-sectional geometryincluding, but not limited to, circular (as illustrated in the exemplaryembodiments of FIGS. 1 and 8), oval, square, rectangular, etc. In anexemplary embodiment, one or more nozzles may be provided associatedwith an exemplary orifice 804 to provide control over one or morecharacteristics of the material solution exiting the reservoir 802through the orifice including, but not limited to, the flow rate, speed,direction, mass, shape and/or pressure of the material solution. Thelocations, cross-sectional geometries and arrangements of the orifices804 on the reservoir 802, and/or the locations, cross-sectionalgeometries and arrangements of the nozzles on the orifices 804, may beconfigured based on the desired characteristics of the resulting fibersand/or based on one or more other factors including, but not limited to,viscosity of the material solution, the rate of solvent evaporationduring fiber formation, etc.

Exemplary orifice lengths that may be used in some exemplary embodimentsrange between about 0.001 m and about 0.1 m, between about 0.001 m andabout 0.01 m, between about 0.001 m and about 0.005 m, between about0.002 m and about 0.005 m, between about 0.001 m and about 0.05 m,between about 0.0015 m and about 0.007 m, between about 0.002 m andabout 0.007 m, between about 0.0025 m and about 0.0065 m, between about0.002 m and about 0.006 m, e.g., about 0.0015, 0.002, 0.0025, 0.003,0.0035, 0.004, 0.0045, 0.005, 0.0055, 0.006, 0.0065, 0.007, 0.0075,0.008, 0.0085, 0.009, 0.0095, 0.01, 0.015, 0.02, 0.025, 0.03, 0.035,0.04, 0.045, 0.05, 0.055, 0.06, 0.065, 0.07, 0.075, 0.08, 0.085, 0.09,0.095, or 0.1 m. Ranges and values intermediate to the above recitedranges and values are also contemplated to be part of the invention.

Exemplary orifice diameters that may be used in some exemplaryembodiments range between about 0.05 μm and about 1000 μm, e.g., betweenabout 0.05 and about 500, between about 0.05 and 100, between about 0.1and 1000, between about 0.1 and 500, between about 0.1 and 100, betweenabout 1 and 1000, between about 1 and 500, between about 1 and 100,between about 10 and 1000, between about 10 and 500, between about 10and 100, between about 50 and 1000, between about 50 and 500, betweenabout 50 and 100, between about 100 and 1000, between about 100 and 500,between about 150 and 500, between about 200 and 500, between about 250and 500, between about 250 and 450, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1,0.15, 0.2, 0.225, 0.25, 0.275, 0.3, 0.325, 0.35, 0.375, 0.4, 0.425,0.45, 0.475, 0.5, 0.525, 0.55, 0.575, 0.6, 0.625, 0.65, 0.675, 0.7,0.725, 0.75, 0.075, 0.8, 0.825, 0.85, 0.825, 0.9, 0.925, 0.95, 0.975,1.0, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9,9.5, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 150, 200, 250, 300, 350,400, 450, 500, 550, 600, 650, 700, 750, 800, 850, 900, 950, or 1000 μm.Ranges and values intermediate to the above recited ranges and valuesare also contemplated to be part of the invention.

The reservoir and collection device may be constructed of any material,e.g., a material that can withstand heat and/or that is not sensitive tochemical organic solvents. In one embodiment, the reservoir and thecollection device are made up of a plastic material, e.g.,polypropylene, polyethylene, or polytetrafluoroethylene. In anotherembodiment, the reservoir and the collection device are made up of ametal, e.g., aluminum, steel, stainless steel, tungsten carbide,tungsten alloys, titanium or nickel. In one embodiment, the collectiondevice is constructed of inert plastic having a melting temperaturegreater than 200° C. In another embodiment, the collection device isconstructed of glass.

Any suitable size or geometrically shaped reservoir or collector may beused in the devices of the invention. For example, the reservoir and/orcollector may be round, rectangular, or oval. The reservoir and/orcollector may be round, oval, rectangular, or a half-heart shape. Thecollector may also be shaped in the form of any living organ, such as aheart, kidney, liver lobe(s), bladder, uterus, intestine, skeletalmuscle, or lung shape, or portion thereof, or, for the fabrication ofprotective clothing, a human head, a torso, a hand, etc. The collectormay further be shaped as any hollow cavity, organ or tissue, such as acircular muscle structure, e.g., a sphincter or iris. These shapes allowthe polymeric fibers to be deposited in the form of a living organ forthe production of engineered tissue and organs, described in more detailbelow. In other embodiments, the collection device is a drum orcylinder, such as a rotating drum or cylinder immersed in a liquid.

In one embodiment, the devices of the invention further comprise acomponent suitable for continuously feeding the polymer into therotating reservoir, such as a spout or syringe pump

The reservoir may also include a heating element for heating and/ormelting the polymer.

In certain embodiments, the collection device is maintained at aboutroom temperature, e.g., about 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, orabout 30° C. and ambient humidity, e.g., about 30, 31, 32, 33, 34, 35,36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53,54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71,72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89,or about 90% humidity. The devices may be maintained at and the methodsmay be formed at any suitable temperature and humidity.

The collection device is suitably sized and may contain about 100, 150,200, 250, 300, 350, 400, 450, 500, 600, 650, 700, 740, 800, 850, 900,950, 1,000, 1,100, 1,200, 1,300, 1,400, 1,500, 1,600, 1,700, 1,800,1,900, 2,000, 2,100, 2,200, 2,300, 2,400, 2,500, 2,600, 2,700, 2,800,2,900, 2,000, 3,00, 3,100, 3,200, 3,300, 3,400, 3,500, 3,600, 3,700,3,800, 3,900, or about 4,000 mls or more of liquid. Values intermediateto the above recited values are also contemplated to be part of theinvention.

In one embodiment of the invention, the device is free of a needle.

In one embodiment, the formed micron, submicron or nanometer dimensionpolymeric fiber is imaged, e.g., using a scanning electron microscope.

Exemplary fiber formation devices may employ one or more mechanisms tocontrol the force and/or speed with which the material jet leaves thereservoir through one or more orifices. In an exemplary embodiment, thespeed (linear and/or rotational) and/or magnitude of the motion (e.g.,the distance traveled by the motion generator along a linear axis) ofthe motion generator may be increased to increase the pressure of thematerial solution in the reservoir which, in turn, increases the forceand/or the speed with which the jets leave the reservoir, and viceversa. In an exemplary embodiment, the material solution may be fed intothe reservoir through an inlet port during fiber formation to increasethe pressure of the material solution in the reservoir which, in turn,increases the force and/or the speed with which the jets leave thereservoir, and vice versa. In an exemplary embodiment, the materialsolution may be fed into the reservoir through the inlet port at afaster or a slower rate to increase or decrease, respectively, thepressure of the material solution in the reservoir. This, in turn,raises or lowers, respectively, the force and/or the speed with whichthe jets leave the reservoir.

Exemplary fiber formation devices may employ the controllable linearmotion of the reservoir to control alignment of the resulting fibers.Controlling one or more aspects of the linear motion of an exemplaryreservoir enables control over the deposition and alignment of eachlayer of polymeric fibers onto the collection device. Exemplary aspectsof the linear motion that may be controlled in exemplary devicesinclude, but are not limited to, the speed of the linear motion of thereservoir, the force and/or speed with which the material jet leaves thereservoir, the dimensions of the reservoir, etc.

In some exemplary embodiments, the speed with which an exemplary motiongenerator oscillates the reservoir and/or the collection device affectsthe pitch of the helical fibers and the spacing between the fibers. Anincreasing vertical speed of the reservoir and/or the collection devicetypically results in an increased pitch of the helical fibers.Accordingly, in an exemplary embodiment, the pitch of the fibers formedis increased by increasing the linear speed of the oscillating reservoirand/or the oscillating collection device along the vertical direction,and vice versa. An increasing vertical speed of the reservoir and/or thecollection device typically results in an increased spacing between thefibers. Accordingly, in an exemplary embodiment, the fiber spacingformed is increased by increasing the linear speed of the oscillatingreservoir and/or the oscillating collection device along the verticaldirection, and vice versa.

In some exemplary embodiments, the polymeric fiber configuration formedon the collection device in exemplary devices of the invention, e.g., amat configuration, a mesh configuration, etc., may be controlled bycontrolling aspects of the linear motion of the reservoir and/or thecollection device. In some exemplary embodiments, the pore sizes formedbetween fibers of a mesh configuration, e.g., larger or smaller poresizes, may be controlled by controlling aspects of the linear motion ofthe reservoir and/or the collection device in exemplary devices. Anincreasing vertical speed of the reservoir and/or collection devicetypically results in larger pore sizes of the fibers, and vice versa.Accordingly, in an exemplary embodiment, the pore sizes of a polymericfiber mesh structure formed is increased by increasing the linear speedof the oscillating reservoir and/or oscillating collection device alongthe vertical direction, and vice versa. Thus, exemplary devices may beused to form fibers of different porosities, e.g., for filters withvarying pore sizes, for a cell-scaffold with a desired pore size whichmay be used to select a desired cell-scaffold infiltration, etc.

In an exemplary embodiment, as the reservoir and/or the collectiondevice is oscillated in a linear manner while the reservoir is beingrotated, the fibers are deposited in a controlled mesh structure,wherein the linear velocity of the reservoir and/or collection devicedetermines the mesh pore size and the pitch of the polymeric fiber meshstructure. The pore size depends on the fiber diameter as well as thefiber pitch. A maximum pore size typically results from large fibers andan approximately 45 degree pitch in one direction. In this exemplaryembodiment, fibers exiting the orifices of the reservoir at anapproximately 45 degree angle in one direction are deposited in anapproximately −45 degree angle in the other direction due to the linearmotion. This results in the formation of layers of fibers that overlapeach other at approximately 90 degrees.

FIG. 2 is a flowchart illustrating an exemplary method 200 for formingor manufacturing an exemplary fiber formation device. In step 202, oneor more reservoirs are provided for holding a material solution. One ormore collection devices for holding a liquid are provided for collectingpolymeric fibers.

In step 204, one or more motion generators are provided for moving thereservoir and/or collection device for fiber formation. In step 206, thereservoir and/or the collection device are coupled to the motiongenerators. In an exemplary embodiment, the motion generators may bedirectly coupled to the reservoir and/or the collection device. Forexample, one or more motors may be provided on or integrally with thereservoir and/or the collection device. In other exemplary embodiments,the motion generators may be coupled to the reservoir and/or thecollection device indirectly using one or more mechanical members, e.g.,rods.

In step 208, one or more power sources and/or motion generator controlmechanisms are provided integrally with the reservoir and/or thecollection device, or separately from the reservoir and/or thecollection device. The power sources, e.g., one or more batteries,provide electrical energy to the motion generators. The motion generatorcontrol mechanisms, e.g., one or more signal generators, control themovement of the motion generators, e.g., activation of the motiongenerators, the speed of the motion generators, the magnitude of themotion of the motion generators, etc. The motion generator controlmechanisms may be used to pre-program the motion of the motiongenerators. The motion generator control mechanisms may be used tostart, stop and alter the motion of the motion generators for a fiberformation session.

FIG. 3 is a flowchart illustrating an exemplary method 300 for using anexemplary fiber formation device to form fibers from a materialsolution. In step 302, an exemplary fiber formation device is provided,for example, in accordance with method 200 illustrated in FIG. 2. Instep 304, the material solution is introduced into the reservoir, forexample, through one or more inlet ports of the reservoir. The materialsolution may be introduced into the reservoir at one time, two or moretimes, continuously or periodically. The volume and flow rate of thematerial solution introduced into the reservoir may be kept constant oraltered based on the requirements of fiber formation. In step 306, aliquid is introduced into the collection device for received materialjets ejected from the reservoir.

In step 308, the reservoir and/or collection device are moved using oneor more motion generators in a rotational and/or linear manner. In step310, the material solution is ejected from the reservoir through one ormore orifices in the reservoir. In step 312, the ejected fibers arereceived in the liquid held in the one or more collection devices, whichcauses formation and solidification of the fibers. In some embodiments,the material solution is ejected from the reservoir through one or moreorifices in the reservoir is initially ejected through an air gapgenerated by a liquid vortex in the liquid in the collection device andsubsequently received in the liquid held in the one or more collectiondevices which cause formation and solidification of the fibers.

In some embodiments, the fibers may be collected from the collectiondevice using any suitable technique. One collection technique involvesmanually extracting the fibers from the liquid in the collection device.Another collection technique involves the use of a spinning around amandrill to wind the fibers and remove them from the liquid. Yet anothercollection techniques involves emptying the liquid which includes thefibers onto a filter and, e.g., applying a vacuum to, e.g., removeexcess water from the fibers (e.g., DNA fibers). In some embodiments,the collected fibers may be mechanically manipulated to adjust thealignment of the fibers and to achieve a desired orientation of thefibers, e.g., by applying uniaxial tension, biaxial tension, and/orshear, and/or by spinning the fibers onto a mandrill.

B. Exemplary Orifices and Nozzles

In exemplary fiber formation devices, an exemplary reservoir includesone or more orifices through which a material solution may be ejectedfrom the reservoir during fiber formation. The devices include asufficient number of orifices for ejecting the polymer during operation,such as 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, or moreorifices. The orifices may be provided on any surface or wall of thereservoir, e.g., side walls, top walls, bottom walls, etc. In exemplaryembodiments in which multiple orifices are provided, the orifices may begrouped together in close proximity to one another, e.g., on the samesurface of the reservoir, or may be spaced apart from one another, e.g.,on different surfaces of the reservoir.

The orifices may be of the same diameter or of different diameters,e.g., diameters of about 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45,0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, 1.0, 2, 3, 4, 5,6, 7, 8, 9, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140,150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280,290, 300, 310, 320, 330, 340, 350, 360, 370, 380, 390, 400, 410, 420,430, 440, 450, 460, 470, 480, 490, 500, 510, 520, 530, 540, 550, 560,570, 580, 590, 600, 610, 620, 630, 640, 650, 660, 670, 680, 690, 700,710, 720, 730, 740, 750, 760, 770, 780, 790, 800, 810, 820, 830, 840,850, 860, 870, 880, 890, 900, 910, 920, 930, 940, 950, 960, 970, 980,990, or about 1000 micrometers. Diameters intermediate to theabove-recited values are also intended to be part of this invention.

The length of the one or more orifices may be the same or different,e.g., diameters of about 0.0015, 0.002, 0.0025, 0.003, 0.0035, 0.004,0.0045, 0.005, 0.0055, 0.006, 0.0065, 0.007, 0.0075, 0.008, 0.0085,0.009, 0.0095, 0.01, 0.015, 0.02, 0.025, 0.03, 0.035, 0.04, 0.045, 0.05,0.055, 0.06, 0.065, 0.07, 0.075, 0.08, 0.085, 0.09, 0.095, or 0.1 m.Lengths intermediate to the above recited lengths are also contemplatedto be part of the invention.

In exemplary fiber formation devices, one or more nozzles may beprovided associated with one or more orifices of a reservoir throughwhich a material solution is ejected from the reservoir. An exemplarynozzle may include a body portion that projects from a side-wall of areservoir substantially orthogonally to the side-wall, and an orifice ata terminal end of the body portion that is exposed to the externalenvironment. A polymer material provided in the reservoir may flow outof the reservoir, through the body portion of the nozzle and out of thenozzle through the orifice of the nozzle in order to form a fiber.

In some exemplary embodiments, exemplary nozzles may be fabricatedseparately from a reservoir and may be patched onto the reservoir. Inother exemplary embodiments, exemplary nozzles may be formed integrallywith a reservoir. In some exemplary embodiments, exemplary nozzles maybe formed of silicon and aluminum using photolithography and DeepReactive Ion etching (DRIE). In some exemplary embodiments, exemplarynozzles may be formed using Focused Ion Beam (FIB) or E-Beam lithographytechniques. In another exemplary embodiment, exemplary nozzles areprovided replaceably on orifices so that one nozzle provided on anorifice may be replaced by another nozzle. In these exemplaryembodiments, the same orifice and the same reservoir may be used to formpolymeric fibers with different surface topographies.

Exemplary nozzles may have cross-sectional configurations and shapesthat impart the configurations to the outer surface of polymeric fibersformed by exemplary fiber formation devices, which increases the surfacearea of the polymeric fibers and the complexity of the surfacetopographies of the polymeric fibers. Exemplary nozzles convolute thesurface of the polymeric fibers and create small structures on thesurface including, but not limited to, projections, ridges, craters,spirals, etc. The fibers formed by exemplary nozzles retain the surfacetopographies and convolutions imparted by the nozzles. Exemplarypolymeric fibers may range in diameter from about 1 nanometer to about100 microns, and exemplary structures may range in size from about 1nanometer to about 500 nanometers. Exemplary polymeric fibers may haveany number of such structures on the outer surface including, but notlimited to, from one to hundreds or thousands.

An exemplary nozzle is provided integrally or removably on a reservoirso that the nozzle is associated with a single orifice. In anotherexemplary embodiment, exemplary nozzles are provided replaceably onorifices so that one nozzle provided on an orifice may be replaced byanother nozzle. In these exemplary embodiments, the same orifice and thesame reservoir may be used to form polymeric fibers with differentsurface topographies.

The convolution of the surface and the structures on the surface of thepolymeric fibers impart unique properties to the fibers. In an exemplaryembodiment, a polymeric fiber with hundreds or thousands of structuralprojections on its surface formed using exemplary nozzles has ahydrophobic property, i.e., the polymeric fibers act similar to a lotusleaf in nature to repel water. In an exemplary embodiment, polymericfibers with high surface areas formed using exemplary nozzles may beused for different applications including, but not limited to,photovoltaic cells, controlled drug delivery, etc. Exemplary polymericfibers with high surface areas formed using exemplary nozzles may beused to increase the tensile strength of already strong fibers, e.g.,poly-paraphenylene terephthalamide, carbon fiber, etc.

An exemplary star shape may have any desired number of points including,but not limited to, three to about a thousand points. Exemplary starpoint lengths (i.e., the length from the center of a star-shaped nozzleto a point of the start shape) may range from about 0.5 microns to about1 mm (e.g., about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 50, 100, 150, 200, 250,300, 350, 400, 450, 500, 600, 650, 700, 750, 800, 850, 900, 950, or 1000microns) in some exemplary embodiments. Lengths intermediate to theabove recited lengths are also contemplated to be part of the invention.

In other exemplary embodiments, the cross-sectional shapes of exemplarynozzles may include asymmetric features to encourage polymeric fibersspiraling as the material solution exits through the nozzles. Thespiraling may be used to form complex polymeric fiber surface textures.In some exemplary embodiments, the cross-sectional shapes of exemplarynozzles may have more complex features than those illustrated including,but not limited to, one or more circular ribbons, one or more circularwavy ribbons, one or more oval ribbons, one or more oval way ribbons,one or more rectangular ribbons, one or more rectangular way ribbons,one or more polygonal ribbons, one or more polygonal wavy ribbons, oneor more multi-point stars (e.g., one or more stars, each having a numberof points that ranges from four to hundreds), one or more slits, one ormore crosses, etc.

In some exemplary embodiments, an exemplary nozzle may have one or morediscrete openings having the same configuration or differentconfigurations. In some exemplary embodiments, the cross-sectionalshapes of exemplary nozzles may include asymmetric features to encouragepolymeric fibers spiraling as the material solution exits through thenozzles. The spiraling may be used to form complex polymeric fibersurface textures. In some exemplary embodiments, the cross-sectionalshapes of exemplary nozzles may have more complex features than thoseillustrated including, but not limited to, one or more circular ribbons,one or more circular wavy ribbons, one or more oval ribbons, one or moreoval way ribbons, one or more rectangular ribbons, one or morerectangular way ribbons, one or more polygonal ribbons, one or morepolygonal wavy ribbons, one or more multi-point stars (e.g., one or morestars, each having a number of points that ranges from four tohundreds), one or more slits, one or more crosses, etc.

C. Use of Exemplary Embodiments in Configuring Fiber Surface Texture andPorosity

Exemplary embodiments may be used to create fibers which have a desiredsurface texture, e.g., rough, smooth, etc. Exemplary embodiments mayalso be used to create fibers and/or multi-fiber structures (e.g.,meshes, mats, etc.) having a desired porosity, i.e., having a desiredpore size.

Fiber surface texture and porosity is a function of different factorsincluding, but not limited to, the rotational and/or linear speed of thereservoir and the mechanical characteristics of the material solution.

In an exemplary embodiment, exemplary fiber formation devices configurethe rotational and/or linear speed of the reservoir to configure theporosity of the fibers. For example, the speed of the reservoir may beincreased to increase the porosity, and vice versa.

In an exemplary embodiment, exemplary fiber formation devices configurethe rotational and/or linear speed of the reservoir to configure thesurface texture of the fibers.

In an exemplary embodiment, the type of material in the materialsolution may be altered to configure the surface texture and porosity ofthe fibers.

In certain embodiments, the fibers may be formed in an environment atexemplary temperatures including, but not limited to, about 20, 21, 22,23, 24, 25, 26, 27, 28, 29, or about 30° C.

In an exemplary embodiment, the nozzles of the reservoir may beconfigured to increase the jet surface area of the material solution.

In other exemplary embodiments, one or more of the above factors may bealtered in combination to affect the surface texture and porosity of thefibers.

D. Exemplary Polymers

Suitable polymers for use in exemplary devices and methods include watersoluble polymers (i.e., polymers dissolved in slowly evaporatingsolvents, e.g., aqueous solvents), polymers that require on-contactcross-linking (e.g., alginate) and/or polymers that cannot be readilydissolved at a high enough concentrations to provide sufficientviscosity for random entanglement and solvent evaporation to formpolymeric fibers (e.g., deoxyribonucleic acid, polyurethane-polyureacopolymer, and polyacrylonitrile), and/or polymers that requireprecipitation (e.g., deoxyribonucleic acid) and/or polymers dissolved inwater at low concentrations (e.g., below 2%), and/or polymers thatrequire both extension in air and precipitation (e.g., polyamides, e.g.,liquid crystalline polymers, e.g., poly-paraphenylene terephthalamide,and poly(p-phenylene benzobisoxazole)).

Suitable polymers may be biocompatible or non-biocompatible, syntheticor natural, e.g., biogenic polymers, e.g., proteins, polysaccharides,lipids, nucleic acids or combinations thereof.

Exemplary polymers which require on-contact crosslinking include, forexample, alginate, gelatin, collagen, chitosan, polyvinyl alcohols,polyacrylamides, starches, and polyethylene oxides, copolymers andderivatives thereof.

Exemplary polymers which require precipitation include, for example,deoxyribonucleic acid, ribonucleic acid, polyurethane-polyureacopolymer, and polyacrylonitrile.

Exemplary polymers which require extension in air and precipitationinclude, for example, polyamides, e.g., liquid crystalline polymers,e.g., poly-paraphenylene terephthalamide, e.g., 1,4-phenylene-diamine(para-phenylenediamine) and terephthaloyl chloride, and poly(p-phenylenebenzobisoxazole)). In one embodiment, the polymer is poly-paraphenyleneterephthalamide.

In certain embodiments of the invention, the methods include mixing abiologically active agent, e.g., a polypeptide, protein, nucleic acidmolecule, nucleotide, lipid, biocide, antimicrobial, or pharmaceuticallyactive agent, with the polymer during the fabrication process of thepolymeric fibers. For example, polymeric fibers prepared using thedevices and methods of the invention may be contacted with encapsulatedfluorescent polystyrene beads.

In other embodiments, a plurality of living cells is mixed with thepolymer during the fabrication process of the polymeric fibers. In suchembodiments, biocompatible polymers (e.g., hydrogels) may be used.

Sufficient speeds and times for operating the devices of the inventionto form a polymeric fiber are dependent on the concentration of thepolymer and the desired features of the formed polymeric fiber.

In one embodiment, the polymer is not sugar, e.g., raw sugar, orsucrose. In another embodiment, the polymer is not floss sugar.

In one embodiment, a polymer for use in the methods of the invention isa synthetic polymer.

In another embodiment, polymers for use in the polymeric fibers of theinvention are not biocompatible.

In yet another embodiment, polymers for use in the polymeric fibers ofthe invention are naturally occurring polymers, e.g., biogenic polymers.Non-limiting examples of such naturally occurring polymers include, forexample, polypeptides, proteins, e.g., capable of fibrillogenesis,polysaccharides, e.g., alginate, lipids, nucleic acid molecules, andcombinations thereof.

In one embodiment, a single polymer is used to fabricate the polymericfibers of the invention. In another embodiment, two, three, four, five,or more polymers are used to fabricate the polymeric fibers of theinvention. In one embodiment the polymers for use in the methods of theinvention may be mixtures of two or more polymers and/or two or morecopolymers. In one embodiment the polymers for use in the methods of theinvention may be a mixture of one or more polymers and or morecopolymers. In another embodiment, the polymers for use in the methodsof the invention may be a mixture of one or more synthetic polymers andone or more naturally occurring polymers.

A polymer for use in the methods of the invention may be fed into thereservoir as a polymer solution. Accordingly, the methods of theinvention may further comprise dissolving the polymer in a solvent(e.g., a non-volatile solution, e.g., an aqueous solution, such aswater, 30% ethanol) prior to feeding the polymer into the reservoir.

In one embodiment, as the polymer is poly-paraphenylene terephthalamideand the methods further comprise dissolving the polymer in sulfuric acidto a concentration of about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13,14, 15, 16, 17, 18, 19 or about 20% weight/volume) at a temperature of,about 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66,67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84,85, 86, 87, 88, 89 or about 90° C.), prior to feeding the solution intothe reservoir.

Alternatively, the polymer may be fed into the reservoir as a polymermelt and, thus, in one embodiment, the reservoir is heated at atemperature suitable for melting the polymer, e.g., heated at atemperature of about 100° C.-300° C., 100° C.-200° C., about 150-300°C., about 150-250° C., or about 150-200° C., 200° C.-250° C., 225°C.-275° C., 220° C.-250° C., or about 100, 105, 110, 115, 120, 125, 130,135, 140, 145, 150, 155, 160, 165, 170, 175, 180, 185, 190, 195, 200,205, 210, 215, 220, 225, 230, 235, 240, 245, 250, 255, 260, 265, 270,275, 280, 285, 290, 295, or about 300° C. Ranges and temperaturesintermediate to the recited temperature ranges are also part of theinvention. In such embodiments, the reservoir may further comprise aheating element.

In one embodiment, the polymeric fibers formed according to the methodsof the invention are further contacted with an agent to produce orincrease the size of pores or number of pores per surface unit area inthe polymeric fibers.

The polymeric fibers formed according to the methods of the inventionmay be contacted with additional agents and optionally cultured in anappropriate medium, such as a tissue culture medium. Contacting thepolymeric fibers with the additional agents will allow the agents to,for example, coat (fully or partially) the fibers, or in the case of forexample cells, to intercalate between fibers. Contacting the polymerwith additional agents during the fabrication of the polymeric fibersalso allows the agents to be incorporated into the polymeric fibersthemselves.

In one embodiment, a plurality of polymeric fibers may be contacted,e.g., seeded, with a plurality of living cells, e.g., vascular smoothmuscle cells, myocytes (e.g., cardiac myocytes), skeletal muscle,myofibroblasts, airway smooth muscle cells, osteoblasts, myoblasts,neuroblasts, fibroblasts, glioblasts, germ cells, hepatocytes,chondrocytes, keratinocytes, connective tissue cells, glial cells,epithelial cells, endothelial cells, vascular endothelial cells,hormone-secreting cells, cells of the immune system, neural cells, andcells that will differentiate into contractile cells (e.g., stem cells,e.g., embryonic stem cells or adult stem cells, progenitor cells orsatellite cells). In one embodiment, polymeric fibers treated with aplurality of living cells may be cultured in an appropriate medium invitro. Such cultured cells exhibit characteristics and functions typicalof such cells in vivo. The plurality of living cells may comprise one ormore types of cells, such as described in U.S. Provisional ApplicationNo. 61/306,736 and PCT Application No. PCT/US09/060224, entitled “TissueEngineered Mycocardium and Methods of Productions and Uses Thereof”,filed Oct. 9, 2009, the entire contents of each of which areincorporated herein by reference.

The cells may be normal cells, abnormal cells (e.g., those derived froma diseased tissue, or those that are physically or genetically alteredto achieve a abnormal or pathological phenotype or function), normal ordiseased muscle cells derived from embryonic stem cells or inducedpluripotent stem cells.

The term “progenitor cell” is used herein to refer to cells that have acellular phenotype that is more primitive (e.g., is at an earlier stepalong a developmental pathway or progression than is a fullydifferentiated cell) relative to a cell which it can give rise to bydifferentiation. Often, progenitor cells also have significant or veryhigh proliferative potential. Progenitor cells can give rise to multipledistinct differentiated cell types or to a single differentiated celltype, depending on the developmental pathway and on the environment inwhich the cells develop and differentiate.

The term “progenitor cell” is used herein synonymously with “stem cell.”

The term “stem cell” as used herein, refers to an undifferentiated cellwhich is capable of proliferation and giving rise to more progenitorcells having the ability to generate a large number of mother cells thatcan in turn give rise to differentiated, or differentiable daughtercells. The daughter cells themselves can be induced to proliferate andproduce progeny that subsequently differentiate into one or more maturecell types, while also retaining one or more cells with parentaldevelopmental potential. The term “stem cell” refers to a subset ofprogenitors that have the capacity or potential, under particularcircumstances, to differentiate to a more specialized or differentiatedphenotype, and which retains the capacity, under certain circumstances,to proliferate without substantially differentiating. In one embodiment,the term stem cell refers generally to a naturally occurring mother cellwhose descendants (progeny) specialize, often in different directions,by differentiation, e.g., by acquiring completely individual characters,as occurs in progressive diversification of embryonic cells and tissues.Cellular differentiation is a complex process typically occurringthrough many cell divisions. A differentiated cell may derive from amultipotent cell which itself is derived from a multipotent cell, and soon. While each of these multipotent cells may be considered stem cells,the range of cell types each can give rise to may vary considerably.Some differentiated cells also have the capacity to give rise to cellsof greater developmental potential. Such capacity may be natural or maybe induced artificially upon treatment with various factors. In manybiological instances, stem cells are also “multipotent” because they canproduce progeny of more than one distinct cell type, but this is notrequired for “stem-ness.” Self-renewal is the other classical part ofthe stem cell definition. In theory, self-renewal can occur by either oftwo major mechanisms. Stem cells may divide asymmetrically, with onedaughter retaining the stem state and the other daughter expressing somedistinct other specific function and phenotype. Alternatively, some ofthe stem cells in a population can divide symmetrically into two stems,thus maintaining some stem cells in the population as a whole, whileother cells in the population give rise to differentiated progeny only.Formally, it is possible that cells that begin as stem cells mightproceed toward a differentiated phenotype, but then “reverse” andre-express the stem cell phenotype, a term often referred to as“dedifferentiation” or “reprogramming” or “retrodifferentiation”.

The term “embryonic stem cell” is used to refer to the pluripotent stemcells of the inner cell mass of the embryonic blastocyst (see U.S. Pat.Nos. 5,843,780, 6,200,806, the contents of which are incorporated hereinby reference). Such cells can similarly be obtained from the inner cellmass of blastocysts derived from somatic cell nuclear transfer (see, forexample, U.S. Pat. Nos. 5,945,577, 5,994,619, 6,235,970, which areincorporated herein by reference). The distinguishing characteristics ofan embryonic stem cell define an embryonic stem cell phenotype.Accordingly, a cell has the phenotype of an embryonic stem cell if itpossesses one or more of the unique characteristics of an embryonic stemcell such that that cell can be distinguished from other cells.Exemplary distinguishing embryonic stem cell characteristics include,without limitation, gene expression profile, proliferative capacity,differentiation capacity, karyotype, responsiveness to particularculture conditions, and the like.

The term “adult stem cell” or “ASC” is used to refer to any multipotentstem cell derived from non-embryonic tissue, including fetal, juvenile,and adult tissue. Stem cells have been isolated from a wide variety ofadult tissues including blood, bone marrow, brain, olfactory epithelium,skin, pancreas, skeletal muscle, and cardiac muscle. Each of these stemcells can be characterized based on gene expression, factorresponsiveness, and morphology in culture. Exemplary adult stem cellsinclude neural stem cells, neural crest stem cells, mesenchymal stemcells, hematopoietic stem cells, and pancreatic stem cells.

In one embodiment, progenitor cells suitable for use in the claimeddevices and methods are Committed Ventricular Progenitor (CVP) cells asdescribed in PCT Application No. PCT/US09/060224, entitled “TissueEngineered Mycocardium and Methods of Productions and Uses Thereof”,filed Oct. 9, 2009, the entire contents of which are incorporated hereinby reference.

Cells for seeding can be cultured in vitro, derived from a naturalsource, genetically engineered, or produced by any other means. Anynatural source of prokaryotic or eukaryotic cells may be used.Embodiments in which the polymeric fibers contacted with a plurality ofliving cells are implanted in an organism can use cells from therecipient, cells from a conspecific donor or a donor from a differentspecies, or bacteria or microbial cells.

In one embodiment of the invention, a plurality of polymeric fibers iscontacted with a plurality of muscle cells and cultured such that aliving tissue is produced. In another embodiment of the invention, aplurality of polymeric fibers is contacted with a plurality of musclecells and cultured such that a living tissue is produced, and the livingtissue is further contacted with neurons, and cultured such that aliving tissue with embedded neural networks is produced.

In one particular embodiment, the living tissue is an anisotropictissue, e.g., a muscle thin film.

In other embodiments of the invention, a plurality of polymeric fibersis contacted with a biologically active polypeptide or protein, such as,collagen, fibrin, elastin, laminin, fibronectin, integrin, hyaluronicacid, chondroitin 4-sulfate, chondroitin 6-sulfate, dermatan sulfate,heparin sulfate, heparin, and keratan sulfate, and proteoglycans. In oneembodiment, the polypeptide or protein is lipophilic.

In still other embodiments, the polymeric fibers are contacted withnucleic acid molecules and/or nucleotides, or lipids.

A plurality of polymeric fibers may also be contacted with apharmaceutically active agent. Suitable pharmaceutically active agentsinclude, for example, anesthetics, hypnotics, sedatives and sleepinducers, antipsychotics, antidepressants, antiallergics, antianginals,antiarthritics, antiasthmatics, antidiabetics, antidiarrheal drugs,anticonvulsants, antigout drugs, antihistamines, antipruritics, emetics,antiemetics, antispasmodics, appetite suppressants, neuroactivesubstances, neurotransmitter agonists, antagonists, receptor blockersand reuptake modulators, beta-adrenergic blockers, calcium channelblockers, disulfiram and disulfiram-like drugs, muscle relaxants,analgesics, antipyretics, stimulants, anticholinesterase agents,parasympathomimetic agents, hormones, anticoagulants, antithrombotics,thrombolytics, immunoglobulins, immunosuppressants, hormoneagonists/antagonists, vitamins, antimicrobial agents, antineoplastics,antacids, digestants, laxatives, cathartics, antiseptics, diuretics,disinfectants, fungicides, ectoparasiticides, antiparasitics, heavymetals, heavy metal antagonists, chelating agents, gases and vapors,alkaloids, salts, ions, autacoids, digitalis, cardiac glycosides,antiarrhythmics, antihypertensives, vasodilators, vasoconstrictors,antimuscarinics, ganglionic stimulating agents, ganglionic blockingagents, neuromuscular blocking agents, adrenergic nerve inhibitors,anti-oxidants, vitamins, cosmetics, anti-inflammatories, wound careproducts, antithrombogenic agents, antitumoral agents, antiangiogenicagents, anesthetics, antigenic agents, wound healing agents, plantextracts, growth factors, emollients, humectants,rejection/anti-rejection drugs, spermicides, conditioners, antibacterialagents, antifungal agents, antiviral agents, antibiotics, biocidalagents, anti-biofouling agents, tranquilizers, cholesterol-reducingdrugs, antitussives, histamine-blocking drugs, or monoamine oxidaseinhibitors.

Other suitable pharmaceutically active agents include growth factors andcytokines. Growth factors useful in the present invention include, butare not limited to, transforming growth factor-α (“TGF-α”), transforminggrowth factor-β (“TGF-β”), platelet-derived growth factors including theAA, AB and BB isoforms (“PDGF”), fibroblast growth factors (“FGF”),including FGF acidic isoforms 1 and 2, FGF basic form 2, and FGF 4, 8, 9and 10, nerve growth factors (“NGF”) including NGF 2.5s, NGF 7.0s andbeta NGF and neurotrophins, brain derived neurotrophic factor, cartilagederived factor, bone growth factors (BGF), basic fibroblast growthfactor, insulin-like growth factor (IGF), vascular endothelial growthfactor (VEGF), granulocyte colony stimulating factor (G-CSF), insulinlike growth factor (IGF) I and II, hepatocyte growth factor, glialneurotrophic growth factor (GDNF), stem cell factor (SCF), keratinocytegrowth factor (KGF), transforming growth factors (TGF), including TGFsalpha, beta, beta1, beta2, and beta3, skeletal growth factor, bonematrix derived growth factors, and bone derived growth factors andmixtures thereof. Cytokines useful in the present invention include, butare not limited to, cardiotrophin, stromal cell derived factor,macrophage derived chemokine (MDC), melanoma growth stimulatory activity(MGSA), macrophage inflammatory proteins 1 alpha (MIP-1alpha), 2, 3alpha, 3 beta, 4 and 5, IL-1, IL-2, IL-3, IL-4, IL-5, IL-6, IL-7, IL-8,IL-9, IL-10, IL-11, IL-12, IL-13, TNF-α, and TNF-β. Immunoglobulinsuseful in the present invention include, but are not limited to, IgG,IgA, IgM, IgD, IgE, and mixtures thereof.

Other agents that may be used to contact the polymeric fibers of theinvention, include, but are not limited to, growth hormones, leptin,leukemia inhibitory factor (LIF), tumor necrosis factor alpha and beta,endostatin, angiostatin, thrombospondin, osteogenic protein-1, bonemorphogenetic proteins 2 and 7, osteonectin, somatomedin-like peptide,osteocalcin, interferon alpha, interferon alpha A, interferon beta,interferon gamma, interferon 1 alpha, amino acids, peptides,polypeptides, and proteins, e.g., structural proteins, enzymes, andpeptide hormones.

For agents such as nucleic acids, any nucleic acid can be used tocontact the polymeric fibers. Examples include, but are not limited todeoxyribonucleic acid (DNA), ent-DNA, and ribonucleic acid (RNA).Embodiments involving DNA include, but are not limited to, cDNAsequences, natural DNA sequences from any source, and sense oranti-sense oligonucleotides. For example, DNA can be naked (e.g., U.S.Pat. Nos. 5,580,859; 5,910,488) or complexed or encapsulated (e.g., U.S.Pat. Nos. 5,908,777; 5,787,567). DNA can be present in vectors of anykind, for example in a viral or plasmid vector. In some embodiments,nucleic acids used will serve to promote or to inhibit the expression ofgenes in cells inside and/or outside the polymeric fibers. The nucleicacids can be in any form that is effective to enhance uptake into cells.

Agents used to treat the polymeric fibers of the invention may also becell fragments, cell debris, organelles and other cell components,tablets, and viruses as well as vesicles, liposomes, capsules,nanoparticles, and other agents that serve as an enclosure formolecules. In some embodiments, the agents constitute vesicles,liposomes, capsules, or other enclosures that contain agents that arereleased at a time after contacting, such as at the time of implantationor upon later stimulation or interaction. In one illustrativeembodiment, transfection agents such as liposomes contain desirednucleotide sequences to be incorporated into cells that are located inor on the polymeric fibers.

Magnetically or electrically reactive materials are examples of otheragents that are optionally used to contact the polymeric fibers of thepresent invention. Examples of magnetically active materials include butare not limited to ferrofluids (colloidal suspensions of magneticparticles), and various dispersions of electrically conducting polymers.Ferrofluids containing particles approximately 10 nanometers indiameter, polymer-encapsulated magnetic particles about 1-2 microns indiameter, and polymers with a glass transition temperature below roomtemperature are particularly useful. Examples of electrically activematerials are polymers including, but not limited to, electricallyconducting polymers such as polyanilines and polypyrroles, ionicallyconducting polymers such as sulfonated polyacrylamides are relatedmaterials, and electrical conductors such as carbon black, graphite,carbon nanotubes, metal particles, and metal-coated plastic or ceramicmaterials.

Suitable biocides for contacting the polymeric fibers of the invention,include, but are not limited to, organotins, brominated salicylanilides,mercaptans, quaternary ammonium compounds, mercury compounds, andcompounds of copper and arsenic.

Antimicrobial agents, which include antibacterial agents, antiviralagents, antifungal agents, and anti-parasitic agents, may also be usedto contact the polymeric fibers of the invention.

The present invention is also directed to the polymeric fibers producedusing the methods and device of the invention, as well as, tissues,membranes, filters, and drug delivery device, e.g., polymeric fiberstreated with, e.g., a pharmaceutically active agent, comprising thepolymeric fibers of the invention.

E. Use of Polymeric Fibers Formed Using Exemplary Embodiments

The polymeric fibers of the invention may be used in a broad range ofapplications, including, but not limited to, use in catalyticsubstrates, photonics, filtration, protective clothing, cellscaffolding, drug delivery and wound healing. Structures prepared usingthe polymeric fibers of the invention are good candidates for tissueengineering due to their high surface to mass ratio, high porosity for,e.g., breathability, encapsulation of active substances and fiberalignment, and because the structures can be easily wound into differentshapes. Tissue engineering applications for structures made using thepolymeric fibers of the invention include, but are not limited toorthopedic, muscular, vascular and neural prostheses, and regenerativemedicines. Madurantakam, et al. (2009) Nanomedicine 4:193-206;Madurantakam, P. A., et al. (2009) Biomaterials 30(29):5456-5464; Xie,et al. (2008) Macromolecular Rapid Communications 29:1775-1792.

Other uses of exemplary fibers include, but are not limited to,manufacture of engineered tissue and organs, including structures suchas patches or plugs of tissues or matrix material, prosthetics, andother implants, tissue scaffolding for, e.g., fractal neural and/orvascular networks, repair or dressing of wounds, hemostatic devices,devices for use in tissue repair and support such as sutures, surgicaland orthopedic screws, and surgical and orthopedic plates, naturalcoatings or components for synthetic implants, cosmetic implants andsupports, repair or structural support for organs or tissues, substancedelivery, bioengineering platforms, platforms for testing the effect ofsubstances upon cells, cell culture, catalytic substrates, photonics,filtration, protective clothing, cell scaffolding, drug delivery, woundhealing, food products, enzyme immobilization, use in a biosensor,forming a membrane, forming a filter, forming a fiber, forming a net,forming a food item, forming a medicinal item, forming a cosmetic item,forming a fiber structure inside a body cavity, forming a non-lethalweapon, forming packaging material (package wrapping material, spillcontainment, e.g., a chemical or oil spill, and the like and numerousother uses.

Mat, mesh and/or woven structures formed with exemplary fibers may beused in non-lethal weapons, for example, nets.

Biogenic polymer fibrous structures may be formed by exemplary fiberformation devices, systems and methods with different and hierarchicalporosities in a single construct. The fibrous structures may, forexample, be used to facilitate nutrition and vascularisation in tissuesat the millimeter scale, to accommodate and mechanically support cellsat the micrometer scale, and to facilitate the expression ofextracellular matrix components with desired chemical and mechanicalfunctions.

Biogenic polymer assemblies with defined dimensional scales formed byexemplary fiber formation devices, systems and methods may be used as awound healing patch to enhance healing processes by providing essentialproteins on or in the wound area to significantly shorten the healingtime.

Biogenic polymers formed by exemplary fiber formation devices, systemsand methods may be used as biofunctional textiles.

One of the benefits of the polymeric fibers of the invention is thatthey can be used to tightly control the biotic/abiotic interface. Inother words, the polymeric fibers of the invention can be used to directthe growth and/or development of specific cell and/or tissue types.

For example, in one embodiment, the polymeric fibers of the inventionmay be used to prepare a membrane, which is useful as, for example, adressing for wounds or injuries of any type. Stem cells, fibroblasts,epithelial cells, and/or endothelial cells may be included to allowtissue growth. In certain embodiments, use of the polymeric fibers will,in addition to providing support, will direct and/or impede desiredcells types to the area of a wound or injury. For example, use of thepolymeric fibers to repair the heart may include the addition of anysuitable substance that will direct cells to differentiate into, forexample, myocytes, rather than, for example, fibroblasts, and/orencourage the migration of a desired cell type to migrate to the area ofthe wound. Such methods will ensure that the repair is biologicallyfunctional and/or discourage, for example restonosis. Such use of thepolymeric fibers may be combined with other methods of treatment,repair, and contouring.

In another embodiment, a polymeric fiber membrane can be inserted as afiller material into wounds to enhance healing by providing a substratethat does not have to be synthesized by fibroblasts and other cells,thereby decreasing healing time and reducing the metabolic energyrequirement to synthesize new tissue at the site of the wound.

Several uses of polymeric fiber membranes are possible in the field ofsurgical repair or construction. For example, membranes of the presentinvention may be used to make tissue or orthopedic screws, plates,sutures, or sealants that are made of the same material as the tissue inwhich the devices will be used.

In other exemplary embodiments, polymeric fiber membranes may be used toform, e.g., a sleeve to use as reinforcement for aneurysms or at thesite of an anastamosis. Such sleeves are placed over the area at whichreinforcement is desired and sutured, sealed, or otherwise attached tothe vessel. Polymeric fiber membranes may also be used as hemostaticpatches and plugs for leaks of cerebrospinal fluid. Yet another use isas an obstruction of the punctum lacryma for a patient suffering fromdry eye syndrome.

Polymeric fiber membranes may also be used to support or connect tissueor structures that have experienced injury, surgery, or deterioration.For example, such membranes may be used in a bladder neck suspensionprocedure for patients suffering from postpartum incontinence. Rectalsupport, vaginal support, hernia patches, and repair of a prolapseduterus are other illustrative uses. The membranes may be used to repairor reinforce weakened or dysfunctional sphincter muscles, such as theesophageal sphincter in the case of esophageal reflux. Other examplesinclude reinforcing and replacing tissue in vocal cords, epiglottis, andtrachea after removal, such as in removal of cancerous tissue.

Other uses for the membranes of the invention include preparing anobstruction or reinforcement for an obstruction to a leak, for example,to seal openings in lungs after lung volume reduction (partial removal).

Another exemplary us of the polymeric fibers of the invention is as abarrier for the prevention of post-operative induced adhesion(s).

Yet another exemplary use of the polymeric fibers of the invention is toserve as a template for nerve growth.

In another embodiment of the invention, the polymeric fibers may be usedto prepare a filter. Such filters are useful for filtration ofcontaminants, biological agents and hazardous but very small particles,e.g., nanoparticles. For example, a polymeric fiber filter of theinvention may be used to purify liquids, such as water, e.g., drinkingwater, oil, e.g., when used in an automobile oil filter. In anotherembodiment, a polymeric fiber filter may be used to purify air when usedin, e.g., a face mask, to filter out viruses, bacteria and hazardousnanoparticles.

The polymeric fibers of the invention may also be incorporated intobiosensor devices, e.g., a device that uses a biological element (e.g.,enzyme, antibody, whole cell, etc.) to monitor the presence of variouschemicals on a substrate by enabling highly specific interactionsbetween biological molecules to be detected and utilized, e.g., as abiorecognition surface. Such biosensors may be used in variousapplications such as the monitoring of pollutants in water, air, andsoil, and in the detection of medically important molecules such ashormones, sugars, and peptides in body fluids, and for pathogendetection.

In yet other embodiments of the invention, the polymeric fibers may beused to prepare textiles. In one embodiment, the textiles are biologicalprotective textiles, e.g., textiles that provide protection from toxicagents, e.g., biological and chemical toxins. For example, the polymericfibers may include, e.g., chlorhexidine, which can kill most bacteria,or an oxime that can break down organophosphates, chemicals that are thebasis of many pesticides, insecticides and nerve gases.

In another embodiment, the polymeric fibers may be used to preparetextiles to prepare personal protection devices and clothing, e.g.,poly-paraphenylene terephthalamide helmets, gloves, and vests. Suchtextiles may be used as clothing for, e g, military service personnel,police department personnel, etc.

In another embodiment, the polymeric fibers comprisingpoly-paraphenylene terephthalamide may be used to may be used to preparetextiles to prepare athletic wear, such as abrasion-resistant athleticwear. For example, the textiles may be used to prepare gloves used byathletes that rock climb or weight lift. Such gloves may protect theathlete's hand from abrasion and/or further injury.

In yet other embodiments, the polymeric fibers comprisingpoly-paraphenylene terephthalamide may be used to be used as a woundcovering to prevent further injury.

In another embodiment, the textiles that contain poly-paraphenyleneterephthalamide, or similar polymers to poly-paraphenyleneterephthalamide may be used to make products more durable. For example,the polymeric fibers may be used in tires, shoes, bags or clothing.

In one embodiment, sheets of polymeric fibers (e.g., sheets ofpoly-paraphenylene terephthalamide nanofibers) are formed using themethods and devices of the invention. Such sheets prepared using thedevices and methods of the present invention do not require thepreparation of yarns or weaving of yarns to prepare a fabric comprisingthe polymeric fibers. Such sheets have the same exemplary uses as thetextiles described supra.

In one embodiment, using the devices and methods of the invention,poly-paraphenylene terephthalamide nanofibers and sheets ofpoly-paraphenylene terephthalamide nanofibers are fabricated. Asdescribed in the appended examples, the fibers and sheets ofpoly-paraphenylene terephthalamide fabricated as described herein arecut- and abrasion-resistant. In contrast, fabrics prepared frompoly-paraphenylene terephthalamide using methods and devices in the artare not cut-resistant unless multiple sheets of the fabric are laminatedor bonded together and/or the fabrics are coated. Accordingly, thesheets and fibers of poly-paraphenylene terephthalamide of the inventionare lighter than the fabrics in the art and have improved mechanicalproperties as compared to the fabrics in the art and may be used as,e.g., personal protection devices and clothing (e.g., bulletproof and/orbladeproof vests, gloves, helmets, etc.), athletic wear (e.g., gloves,shirts, elbow pads, kee pads, etc.), wound coverings, and as a supportto increase product durability.

In embodiments of the invention using poly-paraphenyleneterephthalamide, the devices and methods may be used to produce sheetsof poly-paraphenylene terephthalamide nanofibers with an average spacingbetween fibers of about 300-1000 nm, about 350-1000 nm, about 400-1000nm, about 450-1000 nm, about 300-950 nm, about 350-950 nm, about 400-950nm, about 450-950 nm, about 300-900 nm, about 350-900 nm, about 400-900nm, about 450-900 nm, about 300-850 nm, about 350-850 nm, about 400-850nm, about 450-850 nm, about 300-800 nm, about 350-800 nm, about 400-800nm, about 450-800 nm, about 500-750 nm, or an average spacing of about,e.g., 300, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800, 850, 900,950, or about 1000 nm. Ranges and values intermediate to the aboverecited ranges and values are also contemplated to be part of theinvention.

In some embodiments of the invention using poly-paraphenyleneterephthalamide, the devices and methods may be used to produce sheetsof poly-paraphenylene terephthalamide comprising nanofibers having anaverage diameter of about 0.5-5.0 μm, about 1.0-5.0 μm, about 1.5-5.0μm, about 2.0-5.0 μm, about 0.5-4.5 μm, about 1.0-4.5 μm, about 1.5-4.5μm, about 2.0-4.5 μm, about 0.5-4.0 μm, about 1.0-4.0 μm, about 1.5-4.0μm, about 2.0-4.0 μm, or an average diameter of about 0.5, 0.55, 1, 1.5,2, 2.5, 3, 3.5, 4, 4.5, or about 5 μm. Ranges and values intermediate tothe above recited ranges and values are also contemplated to be part ofthe invention.

In some embodiments of the invention using poly-paraphenyleneterephthalamide, the devices and methods may be used to produce sheetsof poly-paraphenylene terephthalamide comprising nanofibers having anaverage thickness of about 0.1 to about 10 cm. Ranges and valuesintermediate to the above recited ranges and values are alsocontemplated to be part of the invention.

In another embodiment, the polymeric fibers of the invention may be usedto prepare food products. For example, polymeric fibers may be made ofan edible polymer, e.g., alginate, to which a flavoring, e.g., fruitflavoring or chocolate, may be added. In one embodiment, the foodproduct is not cotton candy.

In another embodiment, the polymeric fibers of the invention may be usedto prepare furniture upholstery.

In another embodiment, the polymeric fibers of the invention may be usedto form or manufacture medical devices.

Another use of the polymeric fibers of the present invention is thedelivery of one or more substances to a desired location and/or in acontrolled manner. In some embodiments, the polymeric fibers are used todeliver the materials, e.g., a pharmaceutically active substance. Inother embodiments, the polymeric fibers materials are used to deliversubstances that are contained in the polymeric fibers or that areproduced or released by substances contained in the polymeric fibersmaterials. For example, polymeric fibers containing cells can beimplanted in a body and used to deliver molecules produced by the cellsafter implantation. The present compositions can be used to deliversubstances to an in vivo location, an in vitro location, or otherlocations. The present compositions can be applied or administered tothese locations using any method.

The ability to seed the polymeric fibers of the invention with livingcells also provides the ability to build tissue, organs, or organ-liketissues. Cells included in such tissues or organs can include cells thatserve a function of delivering a substance, seeded cells that willprovide the beginnings of replacement tissue, or both.

In one embodiment of the invention, a plurality of polymeric fibers aretreated with a plurality of living cells and cultured under appropriateconditions to produce a bioengineered tissue.

In some embodiments, polymeric fibers contacted or seeded with livingcells are combined with a drug such that the function of the implantwill improve. For example, antibiotics, anti-inflammatories, localanesthetics or combinations thereof, can be added to the cell-treatedpolymeric fibers of a bioengineered organ to speed the healing process.

Examples of bioengineered tissue include, but are not limited to, bone,dental structures, joints, cartilage, (including, but not limited toarticular cartilage), skeletal muscle, smooth muscle, cardiac muscle,tendons, menisci, ligaments, blood vessels, stents, heart valves,corneas, ear drums, nerve guides, tissue or organ patches or sealants, afiller for missing tissues, sheets for cosmetic repairs, skin (sheetswith cells added to make a skin equivalent), soft tissue structures ofthe throat such as trachea, epiglottis, and vocal cords, othercartilaginous structures such as articular cartilage, nasal cartilage,tarsal plates, tracheal rings, thyroid cartilage, and arytenoidcartilage, connective tissue, vascular grafts and components thereof,and sheets for topical applications, and repair of organs such aslivers, kidneys, lungs, intestines, pancreas visual system, auditorysystem, nervous system, and musculoskeletal system.

In one particular embodiment, a plurality of polymeric fibers arecontacted with a plurality of living muscle cells and cultured underappropriate conditions to guide cell growth with desired anisotropy toproduce a muscle thin film (MTF) or a plurality of MTFs prepared asdescribed in U.S. Patent Publication Nos. 20090317852 and 20120142556,and PCT Application No. PCT/US2012/068787. The entire contents of eachof the foregoing are incorporated herein by reference.

Polymeric fibers contacted with living cells can also be used to produceprosthetic organs or parts of organs. Mixing of committed cell lines ina three dimensional polymeric fiber matrix can be used to producestructures that mimic complex organs. The ability to shape the polymericfibers allows for preparation of complex structures to replace organssuch as liver lobes, pancreas, other endocrine glands, and kidneys. Insuch cases, cells are implanted to assume the function of the cells inthe organs. Preferably, autologous cells or stem cells are used tominimize the possibility of immune rejection.

In some embodiments, polymeric fibers contacted with living cells areused to prepare partial replacements or augmentations. For example, incertain disease states, organs are scarred to the point of beingdysfunctional. A classic example is hepatic cirrhosis. In cirrhosis,normal hepatocytes are trapped in fibrous bands of scar tissue. In oneembodiment of the invention, the liver is biopsied, viable liver cellsare obtained, cultured in a plurality of polymeric fibers, andre-implanted in the patient as a bridge to or replacement for routineliver transplantations.

In another example, by growing glucagon secreting cells, insulinsecreting cells, somatostatin secreting cells, and/or pancreaticpolypeptide secreting cells, or combinations thereof, in separatecultures, and then mixing them together with polymeric fibers, anartificial pancreatic islet is created. These structures are then placedunder the skin, retroperitoneally, intrahepatically or in otherdesirable locations, as implantable, long-term treatments for diabetes.

In other examples, hormone-producing cells are used, for example, toreplace anterior pituitary cells to affect synthesis and secretion ofgrowth hormone secretion, luteinizing hormone, follicle stimulatinghormone, prolactin and thyroid stimulating hormone, among others.Gonadal cells, such as Leydig cells and follicular cells are employed tosupplement testosterone or estrogen levels. Specially designedcombinations are useful in hormone replacement therapy in post andperimenopausal women, or in men following decline in endogenoustestosterone secretion. Dopamine-producing neurons are used andimplanted in a matrix to supplement defective or damaged dopamine cellsin the substantia nigra. In some embodiments, stem cells from therecipient or a donor can be mixed with slightly damaged cells, forexample pancreatic islet cells, or hepatocytes, and placed in aplurality of polymeric fibers and later harvested to control thedifferentiation of the stem cells into a desired cell type. In otherembodiments thyroid cells can be seeded and grown to form small thyroidhormone secreting structures. This procedure is performed in vitro or invivo. The newly formed differentiated cells are introduced into thepatient.

Bioengineered tissues are also useful for measuring tissue activities orfunctions, investigating tissue developmental biology and diseasepathology, as well as in drug discovery and toxicity testing.

Accordingly, the present invention also provides methods for identifyinga compound that modulates a tissue function. The methods includeproviding a bioengineered tissue produced according to the methods ofthe invention, such as a muscle thin film; contacting the bioengineeredtissue with a test compound; and determining the effect of the testcompound on a tissue function in the presence and absence of the testcompound, wherein a modulation of the tissue function in the presence ofthe test compound as compared to the tissue function in the absence ofthe test compound indicates that the test compound modulates a tissuefunction, thereby identifying a compound that modulates a tissuefunction.

In another aspect, the present invention also provides methods foridentifying a compound useful for treating or preventing a disease. Themethods include providing a bioengineered tissue produced according tothe methods of the invention, e.g., a muscle thin film; contacting abioengineered tissue with a test compound; and determining the effect ofthe test compound on a tissue function in the presence and absence ofthe test compound, wherein a modulation of the tissue function in thepresence of the test compound as compared to the tissue function in theabsence of the test compound indicates that the test compound modulatesa tissue function, thereby identifying a compound useful for treating orpreventing a disease.

The methods of the invention generally comprise determining the effectof a test compound on a bioengineered tissue as a whole, however, themethods of the invention may comprise further evaluating the effect of atest compound on an individual cell type(s) of the bioengineered tissue.

The methods of the invention may involve contacting a singlebioengineered tissue with a test compound or a plurality ofbioengineered tissues with a test compound.

As used herein, the various forms of the term “modulate” are intended toinclude stimulation (e.g., increasing or upregulating a particularresponse or activity) and inhibition (e.g., decreasing or downregulatinga particular response or activity).

As used herein, the term “contacting” (e.g., contacting a bioengineeredtissue with a test compound) is intended to include any form ofinteraction (e.g., direct or indirect interaction) of a test compoundand a bioengineered tissue. The term contacting includes incubating acompound and a bioengineered tissue (e.g., adding the test compound to abioengineered tissue).

Test compounds, may be any agents including chemical agents (such astoxins), small molecules, pharmaceuticals, peptides, proteins (such asantibodies, cytokines, enzymes, and the like), and nucleic acids,including gene medicines and introduced genes, which may encodetherapeutic agents, such as proteins, antisense agents (i.e., nucleicacids comprising a sequence complementary to a target RNA expressed in atarget cell type, such as RNAi or siRNA), ribozymes, and the like.

The test compound may be added to a bioengineered tissue by any suitablemeans. For example, the test compound may be added drop-wise onto thesurface of a bioengineered tissue of the invention and allowed todiffuse into or otherwise enter the bioengineered tissue, or it can beadded to the nutrient medium and allowed to diffuse through the medium.In the embodiment where the bioengineered tissue is cultured in amulti-well plate, each of the culture wells may be contacted with adifferent test compound or the same test compound. In one embodiment,the screening platform includes a microfluidics handling system todeliver a test compound and simulate exposure of the microvasculature todrug delivery.

Numerous physiologically relevant parameters, e.g., insulin secretion,conductivity, neurotransmitter release, lipid production, bilesecretion, e.g., muscle activities, e.g., biomechanical andelectrophysiological activities, can be evaluated using the polymericfiber tissues of the invention. For example, in one embodiment, thepolymeric fiber tissues of the present invention can be used incontractility assays for muscular cells or tissues, such as chemicallyand/or electrically stimulated contraction of vascular, airway or gutsmooth muscle, cardiac muscle or skeletal muscle. In addition, thedifferential contractility of different muscle cell types to the samestimulus (e.g., pharmacological and/or electrical) can be studied.

In another embodiment, the bioengineered tissues of the presentinvention can be used for measurements of solid stress due to osmoticswelling of cells. For example, as the cells swell the polymeric fibertissues will bend and as a result, volume changes, force and points ofrupture due to cell swelling can be measured.

In another embodiment, the bioengineered tissues of the presentinvention can be used for pre-stress or residual stress measurements incells. For example, vascular smooth muscle cell remodeling due to longterm contraction in the presence of endothelin-1 can be studied.

Further still, the bioengineered tissues of the present invention can beused to study the loss of rigidity in tissue structure after traumaticinjury, e.g., traumatic brain injury. Traumatic stress can be applied tovascular smooth muscle bioengineered tissues as a model of vasospasm.These bioengineered tissues can be used to determine what forces arenecessary to cause vascular smooth muscle to enter a hyper-contractedstate. These bioengineered tissues can also be used to test drugssuitable for minimizing vasospasm response or improving post-injuryresponse and returning vascular smooth muscle contractility to normallevels more rapidly.

In other embodiments, the bioengineered tissues of the present inventioncan be used to study biomechanical responses to paracrine releasedfactors (e.g., vascular smooth muscle dilation due to release of nitricoxide from vascular endothelial cells, or cardiac myocyte dilation dueto release of nitric oxide).

In other embodiments, the bioengineered tissues of the invention can beused to evaluate the effects of a test compound on anelectrophysiological parameter, e.g., an electrophysiological profilecomprising a voltage parameter selected from the group consisting ofaction potential, action potential duration (APD), conduction velocity(CV), refractory period, wavelength, restitution, bradycardia,tachycardia, reentrant arrhythmia, and/or a calcium flux parameter,e.g., intracellular calcium transient, transient amplitude, rise time(contraction), decay time (relaxation), total area under the transient(force), restitution, focal and spontaneous calcium release. Forexample, a decrease in a voltage or calcium flux parameter of abioengineered tissue comprising cardiomyocytes upon contacting thebioengineered tissue with a test compound, would be an indication thatthe test compound is cardiotoxic.

In yet another embodiment, the bioengineered tissues of the presentinvention can be used in pharmacological assays for measuring the effectof a test compound on the stress state of a tissue. For example, theassays may involve determining the effect of a drug on tissue stress andstructural remodeling of the bioengineered tissues. In addition, theassays may involve determining the effect of a drug on cytoskeletalstructure and, thus, the contractility of the bioengineered tissues.

In still other embodiments, the bioengineered tissues of the presentinvention can be used to measure the influence of biomaterials on abiomechanical response. For example, differential contraction ofvascular smooth muscle remodeling due to variation in materialproperties (e.g., stiffness, surface topography, surface chemistry orgeometric patterning) of bioengineered tissues can be studied.

In further embodiments, the bioengineered tissues of the presentinvention can be used to study functional differentiation of stem cells(e.g., pluripotent stem cells, multipotent stem cells, inducedpluripotent stem cells, and progenitor cells of embryonic, fetal,neonatal, juvenile and adult origin) into contractile phenotypes. Forexample, the polymeric fibers of the invention are treated withundifferentiated cells, e.g., stem cells, and differentiation into acontractile phenotype is observed by thin film bending. Differentiationcan be observed as a function of: co-culture (e.g., co-culture withdifferentiated cells), paracrine signaling, pharmacology, electricalstimulation, magnetic stimulation, thermal fluctuation, transfectionwith specific genes and biomechanical perturbation (e.g., cyclic and/orstatic strains)

In another embodiment, the bioengineered tissues of the invention may beused to determine the toxicity of a test compound by evaluating, e.g.,the effect of the compound on an electrophysiological response of abioengineered tissue. For example, opening of calcium channels resultsin influx of calcium ions into the cell, which plays an important rolein excitation-contraction coupling in cardiac and skeletal musclefibers. The reversal potential for calcium is positive, so calciumcurrent is almost always inward, resulting in an action potentialplateau in many excitable cells. These channels are the target oftherapeutic intervention, e.g., calcium channel blocker sub-type ofanti-hypertensive drugs. Candidate drugs may be tested in theelectrophysiological characterization assays described herein toidentify those compounds that may potentially cause adverse clinicaleffects, e.g., unacceptable changes in cardiac excitation, that may leadto arrhythmia.

For example, unacceptable changes in cardiac excitation that may lead toarrhythmia include, e.g., blockage of ion channel requisite for normalaction potential conduction, e.g., a drug that blocks Na⁺ channel wouldblock the action potential and no upstroke would be visible; a drug thatblocks Ca²⁺ channels would prolong repolarization and increase therefractory period; blockage of K⁺ channels would block rapidrepolarization, and, thus, would be dominated by slower Ca²⁺ channelmediated repolarization.

In addition, metabolic changes may be assessed to determine whether atest compound is toxic by determining, e.g., whether contacting abioengineered tissue with a test compound results in a decrease inmetabolic activity and/or cell death. For example, detection ofmetabolic changes may be measured using a variety of detectable labelsystems such as fluormetric/chrmogenic detection or detection ofbioluminescence using, e.g., AlamarBlue fluorescent/chromogenicdetermination of REDOX activity (Invitrogen), REDOX indicator changesfrom oxidized (non-fluorescent, blue) state to reducedstate(fluorescent, red) in metabolically active cells; Vybrant MTTchromogenic determination of metabolic activity (Invitrogen), watersoluble MTT reduced to insoluble formazan in metabolically active cells;and Cyquant NF fluorescent measurement of cellular DNA content(Invitrogen), fluorescent DNA dye enters cell with assistance frompermeation agent and binds nuclear chromatin. For bioluminescent assays,the following exemplary reagents are used: Cell-Titer Gloluciferase-based ATP measurement (Promega), a thermally stable fireflyluciferase glows in the presence of soluble ATP released frommetabolically active cells.

The bioengineered tissues of the invention are also useful forevaluating the effects of particular delivery vehicles for therapeuticagents e.g., to compare the effects of the same agent administered viadifferent delivery systems, or simply to assess whether a deliveryvehicle itself (e.g., a viral vector or a liposome) is capable ofaffecting the biological activity of the bioengineered tissue. Thesedelivery vehicles may be of any form, from conventional pharmaceuticalformulations, to gene delivery vehicles. For example, the devices of theinvention may be used to compare the therapeutic effect of the sameagent administered by two or more different delivery systems (e.g., adepot formulation and a controlled release formulation). Thebioengineered tissues of the invention may also be used to investigatewhether a particular vehicle may have effects of itself on the tissue.As the use of gene-based therapeutics increases, the safety issuesassociated with the various possible delivery systems becomeincreasingly important. Thus, the bioengineered tissues of the presentinvention may be used to investigate the properties of delivery systemsfor nucleic acid therapeutics, such as naked DNA or RNA, viral vectors(e.g., retroviral or adenoviral vectors), liposomes and the like. Thus,the test compound may be a delivery vehicle of any appropriate type withor without any associated therapeutic agent.

Furthermore, the bioengineered tissues of the present invention are asuitable in vitro model for evaluation of test compounds for therapeuticactivity with respect to, e.g., a muscular and/or neuromuscular diseaseor disorder. For example, the bioengineered tissues of the presentinvention (e.g., comprising muscle cells) may be contacted with acandidate compound by, e g, immersion in a bath of media containing thetest compound, and the effect of the test compound on a tissue activity(e.g., a biomechanical and/or electrophysiological activity) may bemeasured as described herein, as compared to an appropriate control,e.g., an untreated bioengineered tissue. Alternatively, a bioengineeredtissue of the invention may be bathed in a medium containing a candidatecompound, and then the cells are washed, prior to measuring a tissueactivity (e.g., a biomechanical and/or electrophysiological activity) asdescribed herein. Any alteration to an activity determined using thebioengineered tissue in the presence of the test agent (as compared tothe same activity using the device in the absence of the test compound)is an indication that the test compound may be useful for treating orpreventing a tissue disease, e.g., a neuromuscular disease.

Additional contemplated uses of the polymeric fibers of the inventionare disclosed in, for example, PCT Publication Nos.: WO 2008/045506, WO2003/099230, and WO 2004/032713, the entire contents of which areincorporated herein by reference.

This invention is further illustrated by the following examples whichshould not be construed as limiting. The contents of all references,patents and published patent applications cited throughout thisapplication, as well as the Figures, are hereby incorporated herein intheir entirety by reference.

EXAMPLES Example 1. Immersion Rotary Jet Spinning Devices (iRJS) andMethods of Use for the Fabrication of Polymeric Fibers

Although devices and methods for the production of polymeric fibersemploying rotational motion have been previously described (see, e.g.,U.S. Patent Publication No U.S. 2012/0135448 and PCT Publication No.WO2012/068402), fabrication of polymeric fibers using polymers which arewater soluble, and/or those that require on-contact crosslinking and/orprecipitation to form physically and chemically stable polymeric fibersremains challenging. The present invention provides a solution to thisproblem by providing devices, referred to herein as immersion Rotary JetSpinning (iRJS), and methods of use of such devices to fabricatepolymeric fibers, e.g., nanofibers, e.g., isotropically oranisotropically aligned nanofibers (see, e.g., FIGS. 5A-5E). Anexemplary iRJS device is shown in FIG. 1.

The devices of the invention include a collection bath containing aliquid which can be used to crosslink polymers or proteins orprecipitate solid fibers out of solution when shear forces are appliedto a polymer solution as it is forced through an orifice of a rotatingreservoir into the liquid. In other words, shear forces act to elongatethe polymer and reduce the diameter of the polymeric fibers while theliquid aids in solidification.

Two non-limiting examples of polymers suitable for use in the devicesand methods of the present invention are deoxyribonucleic acid (DNA) andalginate.

For example, a solvent for DNA, water, binds strongly to the backbone ofthe DNA molecule. To facilitate solidification and removal of water fromthe polymer jet during spinning, ethanol is placed in the collectiondevice and is used to precipitate the DNA out of the solution.

In another example, alginate (alginic acid) is dissolved in water andrequires a crosslinking agent to form solid materials with long-termstability. Calcium chloride solutions can be used to crosslink alginateinto gels and fibers, but requires a two-step process to achieve. Incontrast, the fabrication of alginate polymeric fibers using an iRJSdevice is a one-step process; iRJS allows for the alginate solution tobe spun into a bath of calcium chloride and form solid and insolublenanofibers during spinning, thereby forming fibers in a one-stepprocess.

Polymer solutions that require on-contact crosslinking and/orprecipitation have been used to fabricate polymeric fibers havingnanometer dimensions using the iRJS devices and methods of the presentinvention. Exemplary DNA and alginate polymeric nanofibers fibers areshown in FIGS. 6A, 6B, 7A, and 7B.

Nanofibers produced by this method may promote migratory cell adhesionfor applications such as wound dressings, clothing, substrates for cellseeding, and coating of implantable devices.

In particular, this technique may be used to fabricate water insoluble,three-dimensional relevant biological scaffolds composed of alginate orDNA nanofibers designed to mimic the extracellular matrix (ECM). The ECMis composed of 3D array fibers on the nanoscale assisting in cellularadhesion (Goodman et al. Biomaterials 1996). The production ofnanofibers as described above may tailor the nanofiber properties tomimic the biological microenvironment of the tissue under study. Afterfabrication by spinning into solution, cells may be seeded to create anassay for the testing the effects of compounds (i.e., pharmaceuticaldrugs) on the tissue in question.

Example 2. Immersion Rotary Jet Spinning of Cut-ResistantPoly-Paraphenylene Terephthalamide Polymeric Fibers

Poly-paraphenylene terephthalamide polymer was dissolved in sulfuricacid at a concentration of 10% weight/volume at 70° C. After solvation,the polymer solution was fed into the reservoir of an iRJS device asdescribed herein. The iRJS device included a reservoir having a 12.5 mmdiameter and a 25.4 mm height, and two orifices, each having a diameterof 340 micrometers, and an orifice length of 4.15 mm. The collectiondevice included a cylinder holding 1.5 L of water, a 11.0 cm stir barand a motion generator to rotate the stir bar at about 350 rpm. Thedistance between the orifice and the liquid in the collection devicebefore operation was 3.5 cm and the distance between the liquid vortexand the orifice during operation was also 3.5 cm.

The reservoir was rotated at 60,000 rpm for 2 minutes, fibers wereejected into the liquid vortex generated by rotating the liquid in thecollection device to form a sheet of solid and insoluble nanofibers in aone-step process. The sheets were removed from the collection deviceusing a rotating drum having a 5.0 cm diameter and a 5.0 cm height. Thedrum was attached to a stir bar and a stabilizing bar. The size of thesheet fabricated was 20.0 cm in length, 2.0 cm in width, and 0.25 cm inthickness (see FIGS. 10A-10E).

In one experiment, a single sheet of poly-paraphenylene terephthalamidenanofibers comprising fibers having a diameter of about 2.0 μm, andabout 0.5 cm in width, 2 cm in length and 0.2 cm in thickness with anapproximate spacing between fibers of about 500 to about 750 nm wasproduced and used for a puncture test. Briefly, about 50 Newtons offorce was applied to a blade that was approximately 0.23 mm thick todetermine whether the sheets could be punctured. Surprisingly, when arazor blade was forced into the nanofiber sheet, the blade did notpuncture the polymer sheet. The same test was performed using a sheet ofpoly-paraphenylene terephthalamide microfibers (e.g. Kevlar; NationalStock Number (NSN): 8470-01-465-1763; Contract #: DAAN02-98-D-5006) thatwas 0.2 cm thick and, in this case, the fibers were cut by the blade(see FIGS. 11A-11D).

While not wishing to be bound by theory, it is believed that the devicesand methods of the claimed invention eject the liquid polymer into theair vortex resulting in extension of the ejected jets of polymer priorto encountering water in the collection device where they then form aliquid crystal permitting molecular interaction between individualfibers to thereby form a dense sheet of nanofibers. Using this one stepprocess for forming sheets of poly-paraphenylene terephthalamidenanofibers, the distance between individual fibers is reduced (ascompared to a fabric of poly-paraphenylene terephthalamide nanofibers,e.g., Kevlar; see FIGS. 11E and 11F), to thereby prepare a sheet offibers that is thinner than other fabrics prepared usingpoly-paraphenylene terephthalamide, and yet is still cut resistant.

The cut-resistance of the poly-paraphenylene terephthalamide nanofibersheets are also assessed using the ASTM F1790 (the standard for theU.S.), ISO 13997 (the international standard) and EN 388 (the EuropeanStandard) test methods.

The ASTM F1790 and the ISO 13997 test methods use the CPP and TDM testmethod which consists of a straight blade that is slid along the lengthof a sample with three different weights. The sample is cut five timesand the data is used to determine the required load needed to cutthrough a sample at a reference distance of 20 mm (0.8″). The EN 388test method uses the Couptest which consists of a circular blade with afixed load that is moved back and forth across the fabric to determinehow long it takes to cut through. Again, 5 cuts are used to determinethe cut index.

The abrasion resistance and puncture resistance of the sheets are alsodetermined using standard methods known in the art, such as the ASTMD4157-13 method to test abrasion resistance and the ASTM F1342 method totest puncture resistance.

Equivalents

In describing exemplary embodiments, specific terminology is used forthe sake of clarity. For purposes of description, each specific term isintended to at least include all technical and functional equivalentsthat operate in a similar manner to accomplish a similar purpose.Additionally, in some instances where a particular exemplary embodimentincludes a plurality of system elements or method steps, those elementsor steps may be replaced with a single element or step. Likewise, asingle element or step may be replaced with a plurality of elements orsteps that serve the same purpose. Further, where parameters for variousproperties are specified herein for exemplary embodiments, thoseparameters may be adjusted up or down by 1/20th, 1/10th, ⅕th, ⅓rd, ½,etc., or by rounded-off approximations thereof, unless otherwisespecified. Moreover, while exemplary embodiments have been shown anddescribed with references to particular embodiments thereof, those ofordinary skill in the art will understand that various substitutions andalterations in form and details may be made therein without departingfrom the scope of the invention. Further still, other aspects, functionsand advantages are also within the scope of the invention.

Exemplary flowcharts are provided herein for illustrative purposes andare non-limiting examples of methods. One of ordinary skill in the artwill recognize that exemplary methods may include more or fewer stepsthan those illustrated in the exemplary flowcharts, and that the stepsin the exemplary flowcharts may be performed in a different order thanshown.

INCORPORATION BY REFERENCE

The contents of all references, including patents and patentapplications, cited throughout this application are hereby incorporatedherein by reference in their entirety. The appropriate components andmethods of those references may be selected for the invention andembodiments thereof. Still further, the components and methodsidentified in the Background section are integral to this disclosure andcan be used in conjunction with or substituted for components andmethods described elsewhere in the disclosure within the scope of theinvention.

We claim:
 1. A device for formation of one or more micron, submicron ornanometer dimension polymeric fibers, the device comprising: a reservoirfor holding a solution comprising a polymer and including a lateralsurface having one or more orifices for ejecting the polymer for fiberformation; a first motion generator comprising a motor, the first motiongenerator configured to impart a rotational motion about an axis ofrotation to the reservoir, the rotational motion of the reservoircausing ejection of the solution comprising the polymer radially outwardwith respect to the axis of rotation from the one or more orifices; acollection device configured to hold a liquid, the collection deviceconfigured and positioned to accept the solution comprising the polymerejected from the reservoir; and a second motion generator comprising astirring element or a drainage system, the second motion generatorcapable of imparting a rotational motion to the liquid in the collectiondevice to generate a liquid vortex resulting in a depression in a topsurface of the liquid in the collection device, and the second motiongenerator being configured such that the reservoir is disposed centrallywith respect to the generated liquid vortex; wherein the reservoir andthe collection device are positioned and configured such that the one ormore orifices of the reservoir eject the polymer into an air gap betweenthe one or more orifices and the liquid held in the collection deviceduring the rotational motion of the reservoir; and wherein the device isconfigured such that the ejection of the solution comprising the polymerinto the air gap and subsequently into the liquid in the collectiondevice via the top surface of the liquid in the collection device causesformation of one or more micron, submicron or nanometer dimensionpolymeric fibers.
 2. The device of claim 1, wherein the device isconfigured such that the air gap between the one or more orifices andthe liquid held in the collection device during the rotational motion ofthe reservoir is due, at least in part, to the liquid vortex generatedby the second motion generator.
 3. The device of claim 1, wherein thedevice is configured such that the one or more orifices of the reservoirare disposed within the depression in the top surface of the liquid inthe collection device caused by the liquid vortex during the rotationalmotion of the reservoir and such that the one or more orifices of thereservoir are positioned below a highest level of the top surface of theliquid in the collection device during the rotational motion of thereservoir.
 4. The device of claim 1, wherein the device is configuredsuch that the air gap is positioned centrally in the liquid vortex inthe collection device.
 5. The device of claim 1, wherein the firstmotion generator and the second motion generator are each configured toimpart rotational motion in the same rotational direction.
 6. The deviceof claim 1, wherein the second motion generator comprises the drainagesystem connected to or couplable to a fluid inlet and a fluid outlet andthat is configured to impart the rotation motion to the liquid in thecollection device by draining the liquid through the drainage system. 7.The device of claim 6, wherein the drainage system is controllable tocontrol a flow rate through the fluid inlet or the fluid outlet.
 8. Thedevice of claim 1, further comprising a collection surface on which theformed fibers collect, the collection surface attached to or coupled tothe second motion generator such that the second motion generatorrotates the collection surface, and wherein the second motion generatorcomprises the stirring element.
 9. The device of claim 8, wherein thecollection surface has a drum or cylinder shape.
 10. A method forfabricating one or more micron, submicron or nanometer dimensionpolymeric fibers, the method comprising: providing the device of claim1; providing the solution comprising the polymer; using the first motiongenerator to rotate the reservoir about the axis of rotation to causeejection of the solution comprising the polymer in one or more jets intothe air gap; collecting the one or more jets of the solution comprisingthe polymer in the liquid of the collection device to cause formation ofthe one or more micron, submicron or nanometer dimension polymericfibers.
 11. The method of claim 10, wherein the one or more micron,submicron or nanometer dimension polymeric fibers are formed byprecipitation of the one or more jets in the liquid of the collectiondevice.
 12. The method of claim 10, wherein the one or more micron,submicron or nanometer dimension polymeric fibers are formed bycross-linking in the one or more jets in the liquid of the collectiondevice.
 13. The method of claim 10, wherein the polymer is selected fromone of the group consisting of a water soluble polymer, a polymer thatrequires on-contact cross-linking, a polymer that cannot be readilydissolved at a concentration that provides a viscosity for randomentanglement and solvent evaporation to form polymeric fibers, and apolymer that requires precipitation.
 14. The method of claim 10, furthercomprising generating the liquid vortex in the collection device usingthe second motion generator during collection of the one or more jets ofthe polymer in the liquid of the collection device.
 15. The method ofclaim 14, further comprising wrapping the polymeric fibers around arotating collection surface.
 16. The method of claim 14, wherein thepolymer is poly-paraphenylene terephthalamide; wherein the liquid in thecollection device comprises water; and wherein the resulting one or moremicron, submicron or nanometer dimension polymeric fibers arepoly-paraphenylene terephthalamide fibers.
 17. A method of forming asheet of micron, submicron or nanometer dimension poly-paraphenyleneterephthalamide fibers, comprising: performing the method of claim 16;and wrapping the polymeric fibers around a rotating collection surfaceduring collection of the polymeric fibers thereby forming the sheet ofmicron, submicron or nanometer dimension polymeric fibers.
 18. Themethod of claim 17, wherein the micron, submicron or nanometer dimensionpoly-paraphenylene terephthalamide fibers of the resulting sheet havinga spacing between fibers of about 300 nm to about 1000 nm.
 19. Themethod of claim 17, wherein the micron, submicron or nanometer dimensionpoly-paraphenylene terephthalamide fibers of the resulting sheet have anaverage diameter in a range of 0.5 μm to about 5 μm.